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371.
US Energy Conservation and Efficiency: Benefits and Costs 总被引:1,自引:0,他引:1
D. Pimentel A. Pleasant J. Barron J. Gaudioso N. Pollock E. Chae Y. Kim A. Lassiter C. Schiavoni A. Jackson M. Lee A. EATON 《Environment, Development and Sustainability》2004,6(3):279-305
With increased energy conservation plus the adoption of diverse energy efficient technologies, the US economy could save about 32 quads or about 33% of its current energy consumption, if sound conservation energy use policies were implemented over approximately 10 years. This potential of 32 quads is slightly greater than the current US oil imports. The systems that have the greatest potential to provide major energy savings are transportation, residential energy use, and the food system. Not only saving energy has merit in itself, but it would save US citizens approximately $438 billion per year, helping support the US economy, a high standard of living, and energy security. In addition, this analysis suggests that reducing the $40 billion in taxpayer money spent on subsidies of the energy industries would further increase conservation. 相似文献
372.
373.
Debera A. Backhus Flynn W. Picardal Scott Johnson Tracy Knowles Richard Collins Anna Radue Sanggoo Kim 《Journal of contaminant hydrology》1997,28(4):337-361
Sorption of organic contaminants to soils has been shown to limit bioavailability and biodegradation in some systems. Use of surfactants has been proposed to reverse this effect. In this study, the effects of a high organic carbon content soil and a nonionic surfactant (Triton X-100) on the reductive dechlorination of carbon tetrachloride (CCl4) were examined in anaerobic systems containing Shewanella putrefaciens. Although more than 70% of the added CCl4 was sorbed to the soil phase in these systems, the reductive dechlorination of CCl4 was not diminished. Rather, rates of CCl4 dechlorination in systems containing soil were enhanced relative to systems containing non-sorptive sand slurries. This enhancement was also observed in sterile soil slurries to which a chemical reductant, dithiothreitol was added. It appears that the organic soil used in these experiments contains some catalytic factor capable of transforming CCl4 in the presence of an appropriate chemical or microbial reductant. The addition of Triton X-100 to sand and soil slurries containing S. putrefaciens resulted in increased CCl4 degradation in both systems. The effect of Triton could not be explained by: (i) surfactant induced changes in the distribution of CCl4, (i.e. decreased sorption) or the rate of CCl4 desorption; (ii) a direct reaction between Triton and CCl4; or (iii) increased cell numbers resulting from use of the surfactant as a substrate. Rather, it appears that Triton X-100 addition resulted in lysis of bacterial cells, a release of biochemical reductant, and enhanced reductive transformation of CCl4. These results provide insights to guide the development of more effective direct or indirect bioremediation strategies. 相似文献
374.
375.
The integration of Landsat TM and environmental GIS data sets using artificial intelligence rule-induction and decision-tree
analysis is shown to facilitate the production of vegetation maps with both floristic and structural information. This technique
is particularly suited to vegetation mapping in disturbed or hilly environments that are unsuited to either conventional remote
sensing methods or GIS modeling using environmental data bases. 相似文献
376.
Wesley P. James Keu Whan Kim 《Journal of the American Water Resources Association》1990,26(4):587-596
ABSTRACT: A distributed watershed model was developed to mathematically simulate overland and channel flow for a single-event storm. The modeled watersheds in the study were subdivided into rectangular grid elements. All hydrologically significant parameters, such as land slope, rainfall and precipitation excess, were assumed to be uniform within each element. The Green-Ampt method was adopted to generate precipitation excess for each element during the simulation period. A two-dimensional diffusion wave model was used for overland flow routing and an iterative Alternative Direction Implicit scheme was used to solve the simultaneous overland flow equations. Once the overland flow became inflow to the channel, a one-dimensional dynamic wave flood routing technique, based on a four-point, implicit, non-linear finite difference solution of the St. Venant equation of unsteady flow, was applied. A limited number of comparisons were made between simulated and observed hydrographs for areas of about one square mile. Given the appropriate parameters, the model was able to accurately simulate runoff for single-event storms. This paper describes a distributed watershed model developed to simulate overland and channel flow. Comparisons were made between simulated and observed hydrographs for three watersheds. The model was able to accurately simulate the runoff for single-event storms using 61-m by 61-m (200 ft by 200 ft) watershed grid elements. 相似文献
377.
A complex chromosome rearrangement, apparently a balanced translocation involving chromosomes 4,6, 15 and 16, was found in cultured cells of amniotic fluid from a 32–year-old primigravida who requested amniocentesis for prenatal diagnosis because of a family history of mental retardation. Chromosome analysis of peripheral blood from both parents were normal. The couple was counselled for the prenatal diagnosis of this de novo complex translocation and, subsequently, elected to terminate the pregnancy. Post-mortem examination revealed a 23–week fetus with intrauterine growth retardation. The identical chromosome rearrangement was subsequently confirmed in cultured fibroblasts from skin and cord obtained from the abortus. To our knowledge, this is the first report where routine prenatal diagnosis revealed a fetus with a balanced complex chromosomal rearrangement involving four chromosomes of de novo origin. 相似文献
378.
379.
Terry W. Snell Julia Kubanek William Carter Audra B. Payne Jerry Kim Melissa K. Hicks Claus-Peter Stelzer 《Marine Biology》2006,149(4):763-773
The defining feature of the life cycle in monogonont rotifers such as Brachionus plicatilis (Muller) is alternation of asexual and sexual reproduction (mixis). Why sex is maintained in such life cycles is an important unsolved evolutionary question and one especially amenable to experimental analysis. Mixis is induced by a chemical signal produced by the rotifers which accumulates to threshold levels at high population densities. The chemical features of this signal were characterized using size exclusion, enzymatic degradation, protease protection assays, selective binding to anion ion exchange and C3 reversed phase HPLC columns, and the sequence of 17 N-terminal amino acids. These studies were carried out over two years beginning in 2003 using B. plicatilis Russian strain. When rotifer-conditioned medium was treated with proteinase K, its mixis-inducing ability was reduced by 70%. Proteinase K was added to medium auto-conditioned by 1 female ml−1 where typically 17% of daughters became mictic and mixis was reduced to 1%. A cocktail of protease inhibitors added to conditioned medium significantly reduced degradation of the mixis signal by natural proteases. Conditioned medium subjected to ultrafiltration retained mixis-inducing activity in the >10 kDa fraction, but the <10 kDa fraction had no significant activity. The putative mixis signal bound to an anion exchange column, eluting off at 0.72 M NaCl. These fractions were further separated on a C3 reversed phase HPLC column and mixis-inducing activity was associated with a 39 kDa protein. Seventeen amino acids from the N-terminus have strong similarity to a steroidogenesis-inducing protein isolated from human ovarian follicular fluid. The 39 kDa protein is an excellent candidate for the rotifer mixis induction signal. 相似文献
380.
The potential of electrokinetic (EK) remediation technology has been successfully demonstrated for the remediation of heavy
metal-contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil
is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic
from two soil samples; a kaolinite soil artificially contaminated with arsenic and an arsenic-bearing tailing-soil taken from
the Myungbong (MB) gold mine area. The effectiveness of enhancing agents was investigated using three different types of cathodic
electrolytes; deionized water (DIW), potassium phosphate (KH2PO4) and sodium hydroxide (NaOH). The results of the experiments on the kaolinite show that the potassium phosphate was the most
effective in extracting arsenic, probably due to anion exchange of arsenic species by phosphate. On the other hand, the sodium
hydroxide seemed to be the most efficient in removing arsenic from the tailing-soil. This result may be explained by the fact
that the sodium hydroxide increased the soil pH and accelerated ionic migration of arsenic species through the desorption
of arsenic species as well as the dissolution of arsenic-bearing minerals. 相似文献