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排序方式: 共有343条查询结果,搜索用时 218 毫秒
191.
ABSTRACT: Modem management concepts were used to increase the efficiency and productivity of a large and complex water resource study conducted on two Delaware River components of the National Wild and Scenic Rivers System. The study analyzed the hydraulics of a 120 mile reach of the river using Rhodamine WT dye injected under medium-flow, low-flow steady-state, and low-flow-surge wave flow conditions. The study benefited from a decentralized management structure that used informal teams to attain quality control objectives, to overcome study difficulties, to secure substantial interagency cooperation, and to maximize limited financial and staffing resources. 相似文献
192.
This study unveils causes of accidents in repair, maintenance, alteration and addition (RMAA) work. RMAA work is playing an increasingly important role in developed societies, including Hong Kong. Safety problems associated with RMAA work in Hong Kong has reached an alarming level. In view of rapid expansion of the RMAA sector and rising proportion of accidents in the construction industry, there is a pressing need to investigate causes of RMAA accidents. Structured interviews were conducted with RMAA contractors to explore causes of accidents in the RMAA sector. A two-round Delphi method with 13 safety experts was subsequently employed to verify the interview findings and rank the relative degree of importance for various causes of accidents. Accidents happen in RMAA work due to intersection of reasons. One of the root causes of accidents in RMAA works is low safety awareness of RMAA workers; however, wider organizational and industrial factors are not negligible. This study sheds light on why accidents happen in the RMAA sector. Only when the factors leading to accidents are identified can effective measures be made. 相似文献
193.
A computation scheme, which involves multi-step computation of the decoupled mass-balance equations in water quality models, was proposed by Park and Kuo (1996. Water Res. 30, 2255–2264). Using a simple hypothetical model, they explained the concept and demonstrated the accuracy and computational efficiency of the multi-step scheme. This paper describes the concept and the implementation of the multi-step computation scheme in a more generalized format for both intratidal and intertidal estuarine water quality models. The scheme is applied to a prototype estuary using a laterally-integrated two-dimensional intratidal model. The computational efficiency of the scheme is demonstrated by comparing the model results using the multi-step scheme with those using the traditional single-step explicit numerical solution of the kinetic processes. 相似文献
194.
Suhett AL Steinberg CE Santangelo JM Bozelli RL Farjalla VF 《Environmental science and pollution research international》2011,18(6):1004-1014
Purpose
Evidence has accumulated that humic substances (HS) are not inert biogeochemicals. Rather, they cause stress symptoms and may modulate the life history of aquatic organisms. Nevertheless, it is still not clear how HS interact with additional stressors and if their effects are transgenerational. We tested the interactive effects of HS and salt to cladocerans, discussing their consequences for the persistence in fluctuating environments, such as coastal lagoons. 相似文献195.
Despite a general decrease in Dutch environmental emission trends, it remains difficult to comply with European Union (EU)
environmental policy targets. Furthermore, environmental issues have become increasingly complex and entangled with society.
Therefore, Dutch environmental policy follows a pragmatic line by adopting a flexible approach for compliance, rather than
aiming at further reduction at the source of emission. This may be politically useful in order to adequately reach EU targets,
but restoration of environmental conditions may be delayed. However, due to the complexity of today’s environmental issues,
the restoration of environmental conditions might not be the only standard for a proper policy approach. Consequently this
raises the question how the Dutch pragmatic approach to compliance qualifies in a broader policy assessment. In order to answer
this question, we adapt a policy assessment framework, developed by Hemerijck and Hazeu (Bestuurskunde 13(2), 2004), based on the dimensions of legitimacy and policy logic. We apply this framework for three environmental policy assessments:
flexible instruments in climate policy, fine-tuning of national and local measures to meet air quality standards, and derogation
for the Nitrate Directive. We conclude with general assessment notes on the appliance of flexible instruments in environmental
policy, showing that a broad and comprehensive perspective can help to understand the arguments to put such policy instruments
into place and to identify trade-offs between assessment criteria. 相似文献
196.
José M. Baldasano María Gonçalves Albert Soret Pedro Jiménez-Guerrero 《Atmospheric environment (Oxford, England : 1994)》2010,44(25):2997-3006
Assessing the effects of air quality management strategies in urban areas is a major concern worldwide because of the large impacts on health caused by the exposure to air pollution. In this sense, this work analyses the changes in urban air quality due to the introduction of a maximum speed limit to 80 km h?1 on motorways in a large city by using a novel methodology combining traffic assimilation data and modelling systems implemented in a supercomputing facility. Albeit the methodology has been non-specifically developed and can be extrapolated to any large city or megacity, the case study of Barcelona is presented here. Hourly simulations take into account the entire year 2008 (when the 80 km h?1 limit has been introduced) vs. the traffic conditions for the year 2007. The data has been assimilated in an emission model, which considers hourly variable speeds and hourly traffic intensity in the affected area, taken from long-term measurement campaigns for the aforementioned years; it also permits to take into account the traffic congestion effect. Overall, the emissions are reduced up to 4%; however the local effects of this reduction achieve an important impact for the adjacent area to the roadways, reaching 11%. In this sense, the speed limitation effects assessed represent enhancements in air quality levels (5–7%) of primary pollutants over the area, directly improving the welfare of 1.35 million inhabitants (over 41% of the population of the Metropolitan Area) and affecting 3.29 million dwellers who are potentially benefited from this strategy for air quality management (reducing 0.6% the mortality rates in the area). 相似文献
197.
The goal of this work was to study long-term behavior of anaerobically digested and dewatered sludge (biosolids) in a lagoon under anaerobic and aerobic conditions to determine the stability of the final product as an indicator of its odor potential. Field lagoons were sampled to estimate spatial and temporal variations in the physical-chemical properties and biological stability characteristics such as volatile solids content, accumulated oxygen uptake, and soluble protein content and odorous compound assessment. The analyses of collected data suggest that the surface layer of the lagoon (depth of above 0.15 m) undergoes long-term aerobic oxidation resulting in a higher degree of stabilization in the final product. The subsurface layers (depth 0.15 m below the surface and deeper) are subjected to an anaerobic environment where the conditions favor the initial rapid organic matter degradation within approximately the first year, followed by slow degradation. 相似文献
198.
N’Guessan Louis Berenger Kouassi Albert Trokourey Metongo Bernard Soro 《Environmental Forensics》2015,16(1):96-108
Metal (Cu, Zn, Pb, Cd, Ni, Co, and Fe) contamination in sediments from a tropical estuary (Ébrié Lagoon, Ivory Coast) was assessed using pollution indices, multivariate analyses and sediment quality guidelines (SQGs). The results demonstrate that increased input of the studied metals occurred over the past 6 years compared to that from 20 years ago, due to rapid population growth, along with the increase of industrial and agricultural activities in the vicinity of the estuary. Ébrié Lagoon was also found to be one of the most contaminated tropical coastal estuaries. Very high average total organic carbon (TOC) content was found (1.9–3.70%) with significant spatial variation as a result of the influence of anthropogenic activities. This study also found that TOC plays an important role in the distribution of Cu, Zn, Co, and Cd in the Ébrié Lagoon sediments. Moderate to high sediment contamination was observed for Cd and Cu, moderate contamination was observed for Zn and Pb, while low contamination was observed for Ni, Co, and Fe. Cluster analysis (CA) and principal component analysis (PCA) investigation revealed that Cu, Zn, Cd, and Co result mainly from anthropogenic sources while Pb, Ni, and Fe may be of natural origin. The pollution-loading index (PLI) indicated that all of the sites close to wastewater discharges were highly polluted. The sediments are likely to be an occasional threat to aquatic organisms due to Cu, Zn, Pb, Cd, and Ni contents, based on the SQGs approach. 相似文献
199.
The Appellate Body report in January 2012 had supported the decision of Panel in the"China-measures related to the exportation of various raw materials"case(WT/DS394,395,398)and affirmed that China's restrictions(such as tariffs and quota measures)on the exportation of raw materials violated rules put forth by the WTO,which were required to be modified.In this case China's right to invoke Article 20 of GATT1994("general exception")to justify its exemption from the guidelines in Article 11.3 of the WTO Accession Protocol was denied by the Panel and the Appellate Body.This was due to the fact that the phrasing in Article 11.3 of Protocol failed to mention"GATT."This was the consequence of the two interpretation approaches the Dispute Settlement Body(DSB)adopted-a narrow textual interpretation and a subjective presumption of"legislative silence."The inappropriate use of the two methods of interpretation lead to an imbalance between the right and obligation of China under the additional obligations that were imposed upon China by the WTO,which create a negative impact on China's rare earth case and the protection of domestic natural resources. 相似文献
200.
Mapping bundles of ecosystem services reveals distinct types of multifunctionality within a Swedish landscape 总被引:1,自引:0,他引:1
Cibele Queiroz Megan Meacham Kristina Richter Albert V. Norström Erik Andersson Jon Norberg Garry Peterson 《Ambio》2015,44(1):89-101
Ecosystem services (ES) is a valuable concept to be used in the planning and management of social–ecological landscapes. However, the understanding of the determinant factors affecting the interaction between services in the form of synergies or trade-offs is still limited. We assessed the production of 16 ES across 62 municipalities in the Norrström drainage basin in Sweden. We combined GIS data with publically available information for quantifying and mapping the distribution of services. Additionally, we calculated the diversity of ES for each municipality and used correlations and k-means clustering analyses to assess the existence of ES bundles. We found five distinct types of bundles of ES spatially agglomerated in the landscape that could be explained by regional social and ecological gradients. Human-dominated landscapes were highly multifunctional in our study area and urban densely populated areas were hotspots of cultural services. 相似文献