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991.
992.
Murphy JJ Dinar A Howitt RE Rassenti SJ Smith VL Weinberg M 《Journal of environmental management》2009,90(2):1089-1096
The main objective of this paper is to design and test a decentralized exchange mechanism that generates the location-specific pricing necessary to achieve efficient allocations in the presence of instream flow values. Although a market-oriented approach has the potential to improve upon traditional command and control regulations, questions remain about how these rights-based institutions can be implemented such that the potential gains from liberalized trade can be realized. This article uses laboratory experiments to test three different water market institutions designed to incorporate instream flow values into the allocation mechanism through active participation of an environmental trader. The smart, computer-coordinated market described herein offers the potential to significantly reduce coordination problems and transaction costs associated with finding mutually beneficial trades that satisfy environmental constraints. We find that direct environmental participation in the market can achieve highly efficient and stable outcomes, although the potential does exist for the environmental agent to influence outcomes. 相似文献
993.
Ingemar Renberg Christian Bigler Richard Bindler Matilda Norberg Johan Rydberg Ulf Segerström 《Journal of environmental management》2009
Establishment of plans for environmental planning and management requires that a number of natural and societal factors must be taken into consideration. Insights into the inherent dynamics of nature as well as the role that past human activities have played for establishing the current condition of the landscape and the natural environment in general are essential. Many natural and man-made changes occur over time scales of decades or centuries, and these are difficult to comprehend without a historical perspective. Such a perspective can be obtained using palaeoecological studies, i.e. by geochemical and biological analyses of lake sediment and peat deposits. To illustrate the long-term dynamics of nature and particularly the role of man, we present here five case studies from Sweden concerning pollution, lake acidification, lake eutrophication, biodiversity, and landscape dynamics and conservation – topics of broad interests – and discuss benefits of including a longer time perspective in environmental management. 相似文献
994.
Contribution of Wastewater Treatment Plant Effluents to Nutrient Dynamics in Aquatic Systems: A Review 总被引:1,自引:0,他引:1
Excessive nutrient loading (considering nitrogen and phosphorus) is a major ongoing threat to water quality and here we review
the impact of nutrient discharges from wastewater treatment plants (WWTPs) to United States (U.S.) freshwater systems. While
urban and agricultural land uses are significant nonpoint nutrient contributors, effluent from point sources such as WWTPs
can overwhelm receiving waters, effectively dominating hydrological characteristics and regulating instream nutrient processes.
Population growth, increased wastewater volumes, and sustainability of critical water resources have all been key factors
influencing the extent of wastewater treatment. Reducing nutrient concentrations in wastewater is an important aspect of water
quality management because excessive nutrient concentrations often prevent water bodies from meeting designated uses. WWTPs
employ numerous physical, chemical, and biological methods to improve effluent water quality but nutrient removal requires
advanced treatment and infrastructure that may be economically prohibitive. Therefore, effluent nutrient concentrations vary
depending on the particular processes used to treat influent wastewater. Increasingly stringent regulations regarding nutrient
concentrations in discharged effluent, along with greater freshwater demand in populous areas, have led to the development
of extensive water recycling programs within many U.S. regions. Reuse programs provide an opportunity to reduce or eliminate
direct nutrient discharges to receiving waters while allowing for the beneficial use of reclaimed water. However, nutrients
in reclaimed water can still be a concern for reuse applications, such as agricultural and landscape irrigation. 相似文献
995.
Margaret A. Palmer Dennis P. Lettenmaier N. LeRoy Poff Sandra L. Postel Brian Richter Richard Warner 《Environmental management》2009,44(6):1053-1068
Rivers provide a special suite of goods and services valued highly by the public that are inextricably linked to their flow
dynamics and the interaction of flow with the landscape. Yet most rivers are within watersheds that are stressed to some extent
by human activities including development, dams, or extractive uses. Climate change will add to and magnify risks that are
already present through its potential to alter rainfall, temperature, runoff patterns, and to disrupt biological communities
and sever ecological linkages. We provide an overview of the predicted impacts based on published studies to date, discuss
both reactive and proactive management responses, and outline six categories of management actions that will contribute substantially
to the protection of valuable river assets. To be effective, management must be place-based focusing on local watershed scales
that are most relevant to management scales. The first priority should be enhancing environmental monitoring of changes and
river responses coupled with the development of local scenario-building exercises that take land use and water use into account.
Protection of a greater number of rivers and riparian corridors is essential, as is conjunctive groundwater/surface water
management. This will require collaborations among multiple partners in the respective river basins and wise land use planning
to minimize additional development in watersheds with valued rivers. Ensuring environmental flows by purchasing or leasing
water rights and/or altering reservoir release patterns will be needed for many rivers. Implementing restoration projects
proactively can be used to protect existing resources so that expensive reactive restoration to repair damage associated with
a changing climate is minimized. Special attention should be given to diversifying and replicating habitats of special importance
and to monitoring populations at high risk or of special value so that management interventions can occur if the risks to
habitats or species increase significantly over time. 相似文献
996.
Improving the Evaluation of Conservation Programs 总被引:5,自引:0,他引:5
Devra G. Kleiman Richard P. Reading † Brian J. Miller † Tim W. Clark ‡ J. Michael Scott § John Robinson Richard L. Wallace ‡§ Robert J. Cabin †† and Fred Felleman‡‡ 《Conservation biology》2000,14(2):356-365
Abstract: The evaluation of conservation programs is rare but increasingly important in improving their effectiveness. Regular evaluations of conservation programs and the implementation of recommendations resulting from such assessments are infrequent because of resistance by participants and lack of funding. Evaluations may be internal or external, depending on the purpose of the review and how broadly it is focused. We strongly recommend external peer review of long-term complex conservation programs every 5 years, supported by more frequent (annual) internal reviews. Criteria for success must encompass both biological and social measures and include learning and the application of new knowledge to management. Evaluations must also go beyond monitoring to assess the value of the program. We emphasize the need to include the organization and function of a conservation program (the process) in any evaluation in addition to substantive criteria for success, which usually involve biological measures (numbers). A dysfunctional program organization and process can as effectively cripple a conservation effort as can a major biological catastrophe. We provide examples of different types of conservation program evaluations, including moderated workshops and case-study analysis, and provide advice on the logistics and organization of the review, emphasizing the importance of the evaluation process itself to a successful outcome. One important aspect of an evaluation is having an individual with leadership ability and considerable expertise to organize the format and oversee the review process itself. Second, it is essential at the outset to ensure agreement among the program participants and the review committee on the goals and objectives of the conservation program, what is to be evaluated, and the criteria for defining success. Finally, the best evaluations are inclusive and involve all participants and stakeholders. 相似文献
997.
Estimate of the Area Affected Ecologically by the Road System in the United States 总被引:45,自引:0,他引:45
Richard T. T. Forman 《Conservation biology》2000,14(1):31-35
Abstract: In view of an extensive road system, abundant and rapidly growing vehicular traffic, and a scattered literature indicating that some ecological effects of roads extend outward for > 100 m, it seems likely that the cumulative ecological effect of the road system in the United States is considerable. Two recent studies in The Netherlands and Massachusetts ( U.S.A.) evaluated several ecological effects of roads, including traffic noise effects, and provide quantitative evidence for a definable "road-effect zone." Based on the approximate width of this asymmetric convoluted zone, I estimate that about one-fifth of the U.S. land area is directly affected ecologically by the system of public roads. I identify a series of assumptions and variables suggesting that over time this preliminary estimate is more likely to rise than drop. Several transportation planning and policy recommendations, ranging from perforating the road barrier for wildlife crossings to closing certain roads, offer promise for reducing this enormous ecological effect. 相似文献
998.
Vector-borne diseases are feared to extend their range in a future where global warming has occurred. There is considerable
concern about scourges such as malaria re-invading currently temperate regions and reaching into higher altitudes in Africa.
In this paper we examine the various factors thought to determine potential infectivity of malaria, and its actual outbreak
in the context of a dynamic integrated assessment model. We quantify: (i) the role of demographics in placing a larger population
in harms way; (ii) the role of climate change in increasing the potential geographic range and severity of the risk of infection;
and (iii) the role of economic and social development in limiting the occurrence of malaria. We then explore the climate and
economic implications of various climate policies in their effectiveness to limit potential infectivity of malaria. In illustration
of these issues we present the climate-related and economics-related impacts of unilateral CO2 control by OECD on incidence of malaria in non-OECD nations. The model presented here, although highly stylized in its representation
of socio-economic factors, provides strong evidence of the role of socio-economic factors in determination of malaria incidence.
The case study offers insights into unintended adverse consequences of well-meaning climate policies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
999.
Wang L Brenden T Seelbach P Cooper A Allan D Clark R Wiley M 《Environmental monitoring and assessment》2008,141(1-3):1-17
Identification of reference streams and human disturbance gradients are crucial steps in assessing the effects of human disturbances
on stream health. We describe a process for identifying reference stream reaches and assessing disturbance gradients using
readily available, geo-referenced stream and human disturbance databases. We demonstrate the utility of this process by applying
it to wadeable streams in Michigan, USA, and use it to identify which human disturbances have the greatest impact on streams.
Approximately 38% of cold-water and 16% of warm-water streams in Michigan were identified as being in least-disturbed condition.
Conversely, approximately 3% of cold-water and 4% of warm-water streams were moderately to severely disturbed by landscape
human disturbances. Anthropogenic disturbances that had the greatest impact on moderately to severely disturbed streams were
nutrient loading and percent urban land use within network watersheds. Our process for assessing stream health represents
a significant advantage over other routinely used methods. It uses inter-confluence stream reaches as an assessment unit,
permits the evaluation of stream health across large regions, and yields an overall disturbance index that is a weighted sum
of multiple disturbance factors. The robustness of our approach is linked to the scale of disturbances that affect a stream;
it will be less robust for identifying less degraded or reference streams with localized human disturbances. With improved
availability of high-resolution disturbance datasets, this approach will provide a more complete picture of reference stream
reaches and factors contributing to degradation of stream health. 相似文献
1000.
Chow JC Watson JG Lowenthal DH Park K Doraiswamy P Bowers K Bode R 《Environmental monitoring and assessment》2008,144(1-3):179-189
PM(2.5) nitrate [Formula: see text] and sulfate ([Formula: see text]) were measured continuously with R&P8400N and R&P8400S instruments, respectively, and compared with filter-based measurements at the Fresno Supersite from October, 2000 through December, 2005. [Formula: see text] concentrations were higher in winter than summer with a long-term decreasing trend. Correlations between 24-h average continuous and filter-based [Formula: see text] were greater than 0.96 in 4 out of 5 years. Continuous [Formula: see text] was generally lower than filter-based [Formula: see text] although the difference decreased over time, from -52% in 2001 to +13% in 2005. These differences were similar in winter (-23%) and summer (-19%) while the corresponding differences between ambient and instrument temperature were -12 and 0.7 degrees C, respectively. Neither seasonal nor long-term trends in [Formula: see text] can be explained by variations in ambient temperature, the difference between ambient and instrument temperature, or changes in aerosol chemical composition. There were no seasonal or long-term trends in [Formula: see text] concentrations, partially due to low concentrations observed in Fresno. Long-term variability in the performance of R&P8400 [Formula: see text] and [Formula: see text] instruments suggest that collocation with filter measurements is needed for long-term measurements. 相似文献