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531.
The realignment and reorganization of ESPR 总被引:1,自引:1,他引:0
532.
533.
Robert F. Young 《Journal of Environmental Planning and Management》2010,53(8):1051-1068
Urban sustainability literature calls for new governance relations to support green urban agendas. Privileging non-hierarchical relations, this literature fails to address the means by which organisations create these capacities. The author interviewed public, private and community environmental leaders in metropolitan Chicago regarding their disposition toward creating boundary spanning organisations (BSOs) in addressing the City's Environmental Action Agenda. Their responses reflect engaged efforts to enhance cross-boundary sharing of information, resources, and power. However, they also reflect the decisive role of central authority in initiating this process. These findings suggest the complexity of urban governance in transitions toward sustainability and the opportunities they provide to explore the implications of on-the-ground practice. 相似文献
534.
Jai-Young Lee Sun Young Youm Sang-Il Choi Byung-Taek Oh 《Journal of Material Cycles and Waste Management》2009,11(3):214-221
The present study investigated the reactivity and ability of permeable reactive barriers [zero-valent iron (ZVI)-barrier plus
biobarrier) to remove various contaminants (Cd, As, Zn, Cu, Mn, Cr, NO3
−, NH4
+, and CODcr) from synthetic leachate. Two different reactive materials were used in this study, namely ZVI and autoclaved lightweight
concrete (ALC). After 90 days of column operation, the contaminant profiles were determined along the length of the columns.
The heavy metals were extensively removed in the bio-ALC and sequential barriers (ZVI plus bio-ALC), however the removal efficiencies
for the heavy metals Zn and Cr in the ALC and bio-ALC barriers were comparatively low. Nitrate was completely removed (>99.9%)
in the ALC, bio-ALC, and sequential barriers. More than 50% of the produced ammonium and organic materials were removed in
the biologically reactive zone of the sequential barriers. The results of the present study suggest that sequential barriers
are one of the best solutions for in situ remediation and that they can be applied to clean up the leachate released from
landfills. 相似文献
535.
This study investigated the reforming characteristics and optimum operating condition of the high-temperature plasma torch (so called plasmatron) for hydrogen-rich gas (syngas) production. At the optimum condition, the composition of produced syngas was 45.4% hydrogen (H2), 6.9% carbon monoxide (CO), 1.5% carbon dioxide (CO2), and 1.1% acetylene (C2H2). The H2/CO ratio was 6.6, hydrogen yield was 78.8%, and the energy conversion rate was 63.6%. To obtain the optimum operating condition, parametric studies were carried out examining the effects of O2/CH4 ratio, steam/CH4 ratio, and Ni catalyst addition in reactor. When the steam/CH4 ratio was 1.23, the production of hydrogen was maximized and the methane conversion rate was 99.7%. The syngas composition was determined to be 50.4% H2, 5.7% CO, 13.8% CO2, and 1.1% C2H2. The H2/CO ratio was 9.7, hydrogen yield was 93.7%, and the energy conversion rate was 78.8%. Hydrogen production with catalyst was effective, compared with no catalyst. 相似文献
536.
Maxted AP Black CR West HM Crout NM McGrath SP Young SD 《Environmental pollution (Barking, Essex : 1987)》2007,150(3):363-372
The objectives of this study were to assess the potential for using Thlaspi caerulescens as a phytoextraction plant and develop a user-advice model, which can predict the frequency of phytoextraction operation required under prescribed conditions. Pot and field trials were conducted using soil collected from a dedicated sewage sludge disposal facility. Soil amendments (sulphuric acid, potassium chloride and EDTA) intended to increase Cd solubility were also tested. Predictive models of Cd and Zn uptake were developed which were able to reproduce the observed pH-dependence of Cd uptake with an apparent maximum around pH 6. Chemical treatments did not significantly increase the uptake of Cd. The periodic use of phytoextraction with T. caerulescens to maintain soils below statutory metal concentration limits, when modern sewage sludges are repeatedly applied, seems very attractive given the non-intrusive and cost-effective nature of the process. The major limitations lie with the large-scale husbandry of T. caerulescens. 相似文献
537.
To analyze polycyclic aromatic hydrocarbons (PAHs) at an urban site in Seoul, South Korea, 24-hr ambient air PM2.5 samples were collected during five intensive sampling periods between November 1998 and December 1999. To determine the PAH
size distribution, 3-day size-segregated aerosol samples were also collected in December 1999. Concentrations of the 16 PAHs
in the PM2.5 particles ranged from 3.9 to 119.9 ng m−3 with a mean of 24.3 ng m−3.An exceptionally high concentration of PAHs(∼120 ng m−3) observed during a haze event in December 1999 was likely influenced more by diesel vehicle exhaust than by gasoline exhaust,
as well as air stagnation, as evidenced by the low carbon monoxide/elemental carbon (CO/EC) ratio of 205 found in this study
and results reported by previous studies.
The total PAHs associated with the size-segregated particles showed unimodal distributions. Compared to the unimodal size
distributions of PAHs with modal peaks at < 0.12 μm measured in highway tunnels in Los Angeles (Venkataraman and Friedlander,
1994), four- to six-ring PAHs in our study had unimodal size distributions, peaking at the larger size range of 0.28–0.53
μm, suggesting the coagulation of freshly emitted ultrafine particles during transport to the sampling site. Further, the
fraction of PAHs associated with coarse particles(> 1.8 μm) increased as the molecular weight of the PAHs decreased due to
volatilization of fine particles followed by condensation onto coarse particles. 相似文献
538.
K. J. Eckelbarger C. M. Young E. Ramirez Llodra S. Brooke P. Tyler 《Marine Biology》2001,138(4):761-775
Gametogenesis, spawning behavior, and early development have been described in the methane-seep polychaete Hesiocaecamethanicola Desbruyères and Toulmond, 1998, the first documentation of the reproductive biology of any cold-seep polychaete species.
The worms were collected at the Green Canyon site in the Gulf of Mexico (27°44.77N; 91°13.33W) in August 1997. The gonads
are situated in the neuropodia in association with an intraepithelial capillary system. Oogenesis is intraovarian, with oocytes
remaining in the ovary until late vitellogenesis when they are released into the coelom for final growth and differentiation.
Vitellogenesis involves both autosynthetic and heterosynthetic processes and, along with ovarian structure, suggests a relatively
slow process of egg formation. Sperm differentiation is intertesticular until early spermiogenesis, when spermatid tetrads
complete development in the coelom. The mature spermatozoon is an ect-aquasperm consisting of a tapering, digitate acrosome,
a spherical nucleus, a midpiece containing from six to eight mitochondria and glycogen stores, and two centrioles associated
with the flagellum. Both sexes undergo broadcast spawning, but the males spawn exclusively through the anus, a behavior previously
unknown in polychaetes. Artificial fertilization resulted in spiral cleavage and development to the trochophore stage. Oocyte
size-frequency analysis of adult females indicates a wide range of oocyte sizes and vitellogenic stages, suggesting that asynchronous
gametogenesis occurs.
Received: 13 July 2000 / Accepted: 29 November 2000 相似文献
539.
Bruce E. Young †††† Karen R. Lips † Jamie K. Reaser ‡ Roberto Ibáñez § Antonio W. Salas J. Rogelio Cedeño †† Luis A. Coloma ‡‡ Santiago Ron ‡‡ Enrique La Marca §§ John R. Meyer Antonio Muñoz ††† Federico Bolaños ‡‡‡ Gerardo Chaves ‡‡‡ David Romo§§§ 《Conservation biology》2001,15(5):1213-1223
Abstract: Although dramatic amphibian population declines have been reported worldwide, our understanding of the extent of the declines in Latin America, where amphibian diversity is high, is limited to a few well-documented studies. To better understand the geographic extent of declines, their possible causes, and the measures needed to improve Latin American scientists' ability to research the phenomenon and make effective management recommendations, we convened three regional workshops with 88 Latin American herpetologists and conservationists. Population declines are widespread in Latin America. At least 13 countries have experienced declines, and in 40 cases species are now thought to be extinct or extirpated in a country where they once occurred. Declines or extinctions have affected 30 genera and nine families of amphibians. Most declines have occurred in remote highlands, above 500 m in elevation in Central America and above 1000 m in the Andes. Most documented declines occurred in the 1980s. Of the possible causes studied to date, climate change appears to be important at one site and chytrid fungal disease has been identified at sites in three countries. Although many monitoring studies are currently underway in a variety of habitats, most studies are recent and of short duration. In a signed resolution, workshop participants called for greater collaboration and communication among scientists working in Latin America to understand the geographic extent of population declines and the distribution of possible causal factors. In situ conservation is important to protect habitats, but captive-rearing programs for species subject to imminent extinction are also needed. Better understanding of the taxonomy and natural history of amphibians and more funding for research and monitoring are critical to developing a scientific basis for management action to arrest and reverse population declines. 相似文献
540.
An electroanalytical method has been developed for the determination of the herbicides ethalfluralin[N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) bezenamine] and methalpropalin [N-(2-methyl-2-propenyl)-2, 6-dinitro-N-propyl-4 (trifluoromethyl) benzenamine] by differential pulse adsorptive stripping voltammetry (DP-AdSV) on a hanging mercury drop electrode (HMDE) with universal buffer as supporting electrolyte. The optimum adsorption conditions were found to be pH 6.0, an accumulation potential of -0.6 V (HMDE vs SCE), an accumulation time of 80 s. and scan rate 45 mVs(-1). Calibration curve is linear in the range 1.30 x 10(-9) to 1.32 x 10(-5) M of ethalfluralin and 1.13 x 10(-5) to 2.0 x 10(-8) M of methalpropalin with detection limits of 1.08 x 10(-9) and 1.87 x 10(-8) M, respectively. The relative SD and correlation coefficients were found to be 1.24%, 0.998 and 1.34%, 0.995, respectively for ten replicates. The method is applied to the determination of the ethalfluralin and methalpropalin in formulations and environmental matrices. 相似文献