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81.
82.
A system combining a national soils database with a neural network was developed for prediction of source location for soil samples. The neural network was trained to predict environmental characteristics, which can be of crucial importance to investigating officers in a police operation or to environmental agencies attempting to locate the source of a pollutant. When coupled with maps of environmental conditions and a generalized opinion pool approach, the system was used to produce weighted maps of source location. The system was capable of reducing search areas of a sample source to less than 0.1% of the total area.  相似文献   
83.
Nutrient enrichment is a frequently cited cause for biotic impairment of streams and rivers in the USA. Efforts are underway to develop nutrient standards in many states, but defensible nutrient standards require an empirical relationship between nitrogen (N) or phosphorus (P) concentrations and some criterion that relates nutrient levels to the attainment of designated uses. Algal biomass, measured as chlorophyll-a (chl-a), is a commonly proposed criterion, yet nutrient-chl-a relationships have not been well documented in Illinois at a state-wide scale. We used state-wide surveys of >100 stream and river sites to assess the applicability of chl-a as a criterion for establishing nutrient standards for Illinois. Among all sites, the median total P and total N concentrations were 0.185 and 5.6 mg L(-1), respectively, during high-discharge conditions. During low-discharge conditions, median total P concentration was 0.168 mg L(-1), with 25% of sites having a total P of > or =0.326 mg L(-1). Across the state, 90% of the sites had sestonic chl-a values of < or =35 microg L(-1), and watershed area was the best predictor of sestonic chl-a. During low discharge there was a significant correlation between sestonic chl-a and total P for those sites that had canopy cover < or =25% and total P of < or =0.2 mg L(-1). Results suggest sestonic chl-a may be an appropriate criterion for the larger rivers in Illinois but is inappropriate for small rivers and streams. Coarse substrate to support benthic chl-a occurred in <50% of the sites we examined; a study using artificial substrates did not reveal a relationship between chl-a accrual and N or P concentrations. For many streams and rivers in Illinois, nutrients may not be the limiting factor for algal biomass due to the generally high nutrient concentrations and the effects of other factors, such as substrate conditions and turbidity.  相似文献   
84.
Large wood (LW) jams are key riverine habitat features that affect hydraulic processes and aquatic habitat. The hydraulic influence of LW jams is poorly understood due to the complexity of fluid dynamics around irregular, porous structures. Here we validated a method for two‐dimensional hydraulic modeling of porous LW jams using the open‐source modeling software Delft3D‐FLOW. We sampled 19 LW jams at three reaches across the Columbia River Basin in the United States. We used computer‐generated porous plates to represent LW jams in the modeling software and calibrated our modeling method by comparing model outputs to measured depths and velocities at validation points. We found that modeling outputs are error‐prone when LW jams are not represented. By representing LW jams as porous plates we reduced average velocity root mean square error (RMSE) values (i.e., improved model accuracy) by 42.8% and reduced average depth RMSE values by 5.2%. These differences impacted habitat suitability index modeling. We found a 15.1% increase in weighted useable area for juvenile steelhead at one test site when LW jams were simulated vs. when they were ignored. We investigated patterns in average RMSE improvements with varying jam size, bankfull obstruction, porosity, and structure type, and river complexity. We also identified research gaps related to field estimation of LW jam porosity and porous structure modeling methods.  相似文献   
85.
Conservation actions, such as habitat protection, attempt to halt the loss of threatened species and help their populations recover. The efficiency and the effectiveness of actions have been examined individually. However, conservation actions generally occur simultaneously, so the full suite of implemented conservation actions should be assessed. We used the conservation actions underway for all threatened and near‐threatened birds of the world (International Union for Conservation of Nature Red List of Threatened Species) to assess which biological (related to taxonomy and ecology) and anthropogenic (related to geoeconomics) factors were associated with the implementation of different classes of conservation actions. We also assessed which conservation actions were associated with population increases in the species targeted. Extinction‐risk category was the strongest single predictor of the type of conservation actions implemented, followed by landmass type (continent, oceanic island, etc.) and generation length. Species targeted by invasive nonnative species control or eradication programs, ex situ conservation, international legislation, reintroduction, or education, and awareness‐raising activities were more likely to have increasing populations. These results illustrate the importance of developing a predictive science of conservation actions and the relative benefits of each class of implemented conservation action for threatened and near‐threatened birds worldwide.  相似文献   
86.
Realizing an effectiveness revolution in environmental management   总被引:2,自引:0,他引:2  
The environmental movement of the 20(th) century has evolved into a large, diverse and well-financed global community that is increasingly required to prove its worth. Though the environmental sector collects and uses data to determine the status of ecological and social systems, the effectiveness of the programs and policies it uses to affect this status remains largely untested. As governments and donor institutions insist on greater transparency, accountability and evidence of what works and what does not, much is being learned from other fields (e.g. health services, education, international development) and increasingly sophisticated approaches are emerging to manage effectiveness. For example, program evaluation, adaptive management, and systematic review provide frameworks and methods to collect and use information to measure and improve performance. However, the critical data and collaborations necessary for an effectiveness revolution are marginalized by technical, cultural and political obstacles. Learning from other fields, the environmental sector must exploit key leverage points, such as flows of information and self-organization, to overcome impediments and create incentives to initiate and realize an era of effectiveness in environmental management.  相似文献   
87.
Abstract

This study examined trends in population redistribution and residential land use changes in northeast Scotland during 1988 to 2003. We utilised a geographical information system (GIS) tool to bring together data from interrelated sources and to analyse population settlement and land use changes at detailed spatial scale. This analysis revealed that substantial land conversion had taken place in the region; particularly conversion of agricultural lands to built-up and residential areas. It also drew attention to policy conflicts, discrepancies between policy rhetoric and policy implementations. More specifically, it was shown that substantial farm land conversion had taken place in suburban areas and rural Aberdeenshire with little change in the size of derelict land in Aberdeen City. The reason given for this was that it was costly to rehabilitate and reuse derelict lands and this conflicted with the objective of providing affordable housing in the City region. The implication of this study is that if the declared policy objectives of integrated and sustainable land use and transport policies are to be achieved, then local authorities may need to cooperate to minimise conflicts between economic and environmental objectives.  相似文献   
88.
An important development in recent years has been increased interest in retrofitting CO2 capture at existing power plants. In parallel, it has also been suggested that flexible operation of power plants with CO2 capture could be important in at least some jurisdictions. It is likely that retrofitted power plants could have significant ??built-in?? flexibility, but this potential is often not considered in studies of the economic performance of power plants with CO2 capture. This paper makes a contribution to filling this gap by developing methods for first order screening analysis of flexible operation of power plants with CO2 capture and applying them to the case study example of an appropriately integrated retrofit of post-combustion capture at a coal-fired power plant. The quantitative analysis suggests that rich solvent storage could be an attractive option on a short-run basis for some fuel, CO2 and electricity price combinations. Results from first order analysis can then be used to determine which operating modes should (and shouldn??t) be included in further, more detailed design studies.  相似文献   
89.
As community-based natural resource management (CBNRM) increases in popularity, the question of the capacity of such groups to successfully manage natural resources becomes increasingly relevant. However, few studies have quantifiably analyzed how the amount or type of capacity in a CBNRM organization directly affects the outputs or the environmental outcomes produced. This paucity of research exists in part due to the diversity of indicators for CBNRM group capacity, as well as the ensuing debate over how to best define and measure success in CBNRM initiatives. Although concrete outputs vary widely, many efforts center on creating natural resource management plans (RMPs). The primary objective of our research was to explore the link between capacity and RMP implementation success, as perceived by practitioners among CBNRM groups across Illinois. A short online survey was constructed, utilizing findings from focus groups in combination with an extensive literature review, to measure CBNRM participants’ (n = 190) perceptions of 10 key capacity indicators and RMP implementation success. Results show that capacity perceptions varied significantly among respondents in low, moderate, and high RMP implementation success groups, and that group capacity was predictive of the degree of perceived RMP implementation success. Further, our findings suggest that bonding social capital and outreach are crucial in predicting low versus moderate RMP success, while leadership, motivation, and vision best distinguish the moderately successful and highly successful groups.  相似文献   
90.
The influence of specific stressors, such as nutrient enrichment and physical habitat degradation, on biotic integrity requires further attention in Midwestern streams. We sampled 53 streams throughout Illinois and examined relationships between macroinvertebrate community structure and numerous physicochemical parameters. Streams were clustered into four major groups based on taxa dissimilarity. Habitat quality and dissolved nutrients were responsible for separating the major groups in a nonmetric multidimensional scaling ordination. Furthermore, the alignment of environmental factors in the ordination suggested there was a habitat quality-nutrient concentration gradient such that streams with high-quality habitats usually had low concentrations of nutrients. Discrimination by community measures further validated the major stream groups and indicated that forested streams had generally higher biological integrity than agricultural streams, which in turn had greater integrity than urban streams. Our results demonstrate that physical habitat degradation and nutrient pollution are important and often confounded determinants of biotic integrity in Illinois streams. In addition, we suggest that management of Midwestern streams could benefit from further implementation of multivariate data exploration and stream classification techniques.  相似文献   
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