排序方式: 共有55条查询结果,搜索用时 0 毫秒
51.
Clair Gough Nuria Castells Silvio Funtowicz 《Environmental Modeling and Assessment》1998,3(1-2):19-29
Over recent years Integrated Assessment (IA) has been presented as a new and innovative approach to modern decision making. In this paper we explore some of the key features that we consider characterise IA; we present IA as a framework that allows a flexible approach to uncertainty in decision making and to which a broad palette of expertise can contribute. The example of the development of an international agreement to reduce acidic deposition is used to illustrate the current practical status of an IA. The scientific process leading to this agreement has previously been described as IA but we argue that, although it marks a change from traditional approaches, further progress is still required to satisfy the requirements for a successful and durable IA. 相似文献
52.
Stephen M. Born Kenneth D. Genskow Timothy L. Filbert Nuria Hernandez-Mora Matthew L. Keefer Kimberly A. White 《Environmental management》1998,22(3):359-370
/ There are tens of thousands of small dams in the United States; many of these aging structures are deteriorating. Governments and dam owners face decisions regarding repair or removal of these structures. Along with the many benefits society derives from dams and their impoundments, numerous recent ecological studies are revealing the extensive alteration and degradation of river ecosystems by dams. Dam removal-a principal restoration strategy-is an infrequent event. The major reasons for removal have been public safety and the high costs associated with repair; the goal of river ecosystem restoration now warrants greater attention. Substantial study is being given to the environmental aspects of dams and dam removals, but very little attention has been given to the socioeconomic and institutional dimensions associated with the removal of dams, although these factors play a significant role in the removal decision-making process. Based on a case study of dam removals in Wisconsin-where more than 30 of the state's 3600 small dams have been removed in the past few decades-legal, financial, and socioeconomic issues associated with dam removal are documented and assessed. Dam removal has been complex and contentious, with limited community-based support for removal and loss of the impounded waters. In cases examined here, the estimated costs of repairing a dam averaged more than three times the cost of removal. The availability of governmental financing has been a key determinant in removal decisions. Watershed-scale ecological considerations are not major factors for most local interests. As watershed management and restoration increasingly include dam removal options as part of an integrated strategy, more attention will need to be focused on socioeconomic factors and stakeholder perspectives-variables that strongly influence the viability of this management alternative.KEY WORDS: Dam removal; River restoration; Institutions; Stakeholders 相似文献
53.
Castell-Balaguer N Téllez L Mantilla E 《Environmental science and pollution research international》2012,19(8):3461-3480
Introduction
The Turia river basin, located in the east of the Iberian Peninsula, drains into the Mediterranean Sea near the city of Valencia (population, 814,208). The predominance of sea-breeze fluxes favours the inland transport of pollutants from the city up the basin where ozone concentrations exceeding the threshold for protection of human health are systematically recorded during the summer months.Methods
This work analyses the variability in ozone levels by examining their spatial and temporal distribution in a Mediterranean river basin downwind from a city within the period 2005?C2008. Orographic determinants and atmospheric fluxes induce strong variations in ozone measurements, even on relatively close locations.Conclusions
Results show a different behaviour of the monthly means and the daily cycles depending on the season of the year and the measuring environment, with summer/winter ratios ranging from 2.4 in cities to 1.6 inland, and mean values always higher in the interior of the basin. Daily cycles show significant summer/winter differences related to the predominant situations of anticyclonic stability in winter, which limit ventilation, and the predominant breeze circulations in summer. Results also show a ??weekend effect?? at urban and medium-distance stations. At the most inland station, the weekend/weekday behaviour differs according to the season of the year; weekend ozone levels are higher in spring, autumn and winter, and lower in summer, coinciding with the predominance of local wind cycles that favour air mass penetration inland from the coast. 相似文献54.
Nuria Castell Enrique Mantilla Ariel F. Stein Rosa Salvador Millán Millán 《Environmental Modeling and Assessment》2011,16(6):565-576
During the central months of the year, southwestern Spain is under strong insolation and weak synoptic forcing, promoting
the development of sea breezes and mountain-induced winds and creating recirculations of pollutants. The complex topography
of the Southwestern Iberia Peninsula induces the formation of vertical layers, into which the pollutants are injected and
subjected to long-distance transport and compensatory subsidence. The characteristics of these highly complex flows have important
effects on the pollutant dispersion. Air pollution studies in very complex terrains require high-resolution modelling for
resolving the flow dynamics. This paper shows the results obtained from using the MM5-CAMx multiscale-nested air quality model
to relate the sensitivity regimes for ozone, nitrogen oxides and volatile organic compounds in an area of high geographical
complexity. The article assesses the impact on the hourly and eight-hourly maximum daily ozone concentrations of four reduction
strategies during two ozone pollution episodes. This analysis of the ozone response has led to a preliminary evaluation of
the effectiveness of the most common control strategies: traffic, industry, mixed traffic and industry, and closure of some
of the largest industries (oil and petrochemical refineries). Photochemical indicators show that ozone chemistry in southwestern
Spain is strongly sensitive to NO
x
. However, volatile organic compound-sensitive points are found in areas with anthropogenic influence (highways, cities and
industrial parks). Our results indicate that reductions in road traffic lead to ozone reductions over large areas, whereas
reductions in industrial emissions, despite sometimes showing greater decreases in the maximum hourly and eight-hourly ground-level
ozone levels, lead to ozone reductions in a local area only. In the control study case, with the oil refinery and the petrochemical
plants closed, decreases in ozone hourly concentrations are up to 40% higher than in the other emission control scenarios
studied. This analysis provides an assessment of the effectiveness of different policies for controlling precursor emissions
by comparing the modelled results for different scenarios. 相似文献
55.
Varea M Galindo N Gil-Moltó J Pastor C Crespo J 《Journal of environmental monitoring : JEM》2011,13(9):2471-2476
Particle-bound PAHs were measured at three sites in southeastern Spain (an urban background location, a suburban-industrial site in the vicinity of two cement plants and a rural area) in order to investigate the influence of the type of location on PAH concentrations. A clear influence of cement production on particulate PAH levels could not be established since for the urban background and suburban-industrial sites the average concentrations of total PAHs in the PM2.5 fraction were very similar (1.085 and 1.151 ng m(-3), respectively), with benzo[b+k]fluoranthene and chrysene as the predominant compounds. Diagnostic ratios, used to identify PAH emission sources, pointed to traffic as the main source of particulate PAH at both locations. As expected, PAH levels at the rural site were significantly lower (0.408 ng m(-3) in the PM10 fraction) due to increasing distance from the emission sources. PAH seasonal variations at the urban background and suburban-industrial sites were the same as reported in many previous studies. Average winter to summer ratios for total PAHs were 4.4 and 4.9 for the urban background and industrial sites, in that order. This seasonal cycle could be partially explained by the higher temperature and solar radiation during summer enhancing PAH evaporation from the particulate phase and PAH photochemical degradation, respectively. The study of PAH distribution between the fine and coarse fraction at the urban site revealed that on average around 80% of total PAHs were associated with fine particles. 相似文献