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排序方式: 共有171条查询结果,搜索用时 15 毫秒
71.
Donald A. Schultz Ronald L. Raschke Roxanne Jones 《Environmental monitoring and assessment》1994,32(3):201-205
The Algal Growth Potential Test has been an accepted standard test for measuring the bioavailability of nutrients in water bodies. A shortened seven day test has been developed, tested, and shown to have a strong correlation relationship with algal tests grown to maximum dry weight yields. The new test will save time in processing the samples and processing of test data. 相似文献
72.
Wesley H. Blood Calvin G. Clyde Dean F. Peterson 《Journal of the American Water Resources Association》1971,7(4):785-801
ABSTRACT .Desalting plants can provide a means of firming up erratic natural supplies when properly operated in conjunction with existing water supply reservoir systems. Since the natural inflow is variable, the choice of when to run the desalting plant is difficult. If the plant is turned on too late, a shortage may result; or if the plant runs too long, costly water may be wasted. A computer program is described that can help water planners find an optimal operating rule, i.e., a policy that tells when to turn the plant on and off to meet a given demand. Criteria for defining the firm water yield of the system (with and without desalting) are first defined. The logic of the program is then described. The program, written in FORTRAN IV, successively simulates operation of the given size reservoir-desalting plant system under control of various operating rules and selects the optimal rule as the one which produces the required firm water yield at the least unit cost. The optimal plant size and the staging of construction can also be studied by making a series of computations. Applications of the Operating Rule Program to water systems in California, Utah and New York are described. The studies show that, compared with base load operation, substantial savings are possible if optimum intermittent conjunctive operation of the desalting plant is followed. 相似文献
73.
Katrine Uhrbrand Anna Charlotte Schultz Anne Mette Madsen 《Food and environmental virology》2011,3(3-4):130-137
Exposure to bioaerosols associated with wastewater treatment processes may represent an occupational health risk for workers at wastewater treatment plants (WWTPs). A high frequency of acute symptoms in the gastrointestinal tract among the wastewater workers at a Danish WWTP has been reported. The objective of the study was therefore to examine the exposure of the workers to aerosolised microorganisms. Sampling of inhalable endotoxin, bacteria, moulds and viruses was performed on one occasion using personal samplers. Noroviruses (NoVs) and endotoxin were detected at concentrations that could pose an occupational health risk and possibly contribute to the increased frequency of gastrointestinal illness among the workers and should therefore be investigated further. In addition, positive correlations between exposure to endotoxin, bacteria, moulds and NoVs were found and indicate that the exposure to bioaerosols may be related to work tasks. This is the first study directly showing an occupational exposure to airborne NoVs by its detection in airborne dust. 相似文献
74.
C.L. Schultz S.N. Ahmed R. Mandel H.L.N. Moltz 《Journal of the American Water Resources Association》2014,50(4):909-927
We have enhanced the ability of a widely used watershed model, Hydrologic Simulation Program — FORTRAN (HSPF), to predict low flows by reconfiguring the algorithm that simulates groundwater discharge. During dry weather periods, flow in most streams consists primarily of base flow, that is, groundwater discharged from underlying aquifers. In this study, HSPF's groundwater storage‐discharge relationship is changed from a linear to a more general nonlinear relationship which takes the form of a power law. The nonlinear algorithm is capable of simulating streamflow recession curves that have been found in some studies to better match observed dry weather hydrographs. The altered version of HSPF is implemented in the Chesapeake Bay Program's Phase 5 Model, an HSPF‐based model that simulates nutrient and sediment loads to the Chesapeake Bay, and is tested in the upper Potomac River basin, a 29,950 km2 drainage area that is part of the Bay watershed. The nonlinear relationship improved median Nash‐Sutcliffe efficiencies for log daily flows at the model's 45 calibration points. Mean absolute percent error on low‐flow days dropped in five major Potomac River tributaries by up to 12 percentage points, and in the Potomac River itself by four percentage points, where low‐flow days were defined as days when observed flows were in the lowest 5th percentile range. Percent bias on low‐flow days improved by eight percentage points in the Potomac River, from ?11 to ?3%. 相似文献
75.
Flood‐related losses in the United States are increasing despite large‐scale mitigation efforts. To offset the rising cost of floods, the US Congress passed legislation in 2014 that will augment insurance premiums to make the National Flood Insurance Program more actuarially sound. Consequently, there is interest in lowering flood‐related costs to the homeowner, both in terms of premiums and damage. This study addresses the issue by integrating premium savings and damages avoided based on several mitigation scenarios. Specifically, it examines how much policyholders within a watershed near Houston, Texas, could have saved between 1999 and 2009 had their communities introduced specific avoidance‐based mitigation activities. The results indicate that homeowners and communities can offset premium rises and a majority of the damage suffered through marginal expansions of such initiatives. However, the costs associated with their implementation could counter some of these savings, and hence they need to be considered in future work. 相似文献
76.
Reed F. Noss Jennifer M. Cartwright Dwayne Estes Theo Witsell Gregg Elliott Daniel Adams Matthew Albrecht Ryan Boyles Patrick Comer Chris Doffitt Don Faber-Langendoen JoVonn Hill William C. Hunter Wesley M. Knapp Michael E. Marshall Jason Singhurst Christopher Tracey Jeffrey Walck Alan Weakley 《Conservation biology》2021,35(6):1715-1724
Despite its successes, the U.S. Endangered Species Act (ESA) has proven challenging to implement due to funding limitations, workload backlog, and other problems. As threats to species survival intensify and as more species come under threat, the need for the ESA and similar conservation laws and policies in other countries to function efficiently has grown. Attempts by the U.S. Fish and Wildlife Service (USFWS) to streamline ESA decisions include multispecies recovery plans and habitat conservation plans. We address species status assessment (SSA), a USFWS process to inform ESA decisions from listing to recovery, within the context of multispecies and ecosystem planning. Although existing SSAs have a single-species focus, ecosystem-based research can efficiently inform multiple SSAs within a region and provide a foundation for transition to multispecies SSAs in the future. We considered at-risk grassland species and ecosystems within the southeastern United States, where a disproportionate number of rare and endemic species are associated with grasslands. To initiate our ecosystem-based approach, we used a combined literature-based and structured World Café workshop format to identify science needs for SSAs. Discussions concentrated on 5 categories of threats to grassland species and ecosystems, consistent with recommendations to make shared threats a focus of planning under the ESA: (1) habitat loss, fragmentation, and disruption of functional connectivity; (2) climate change; (3) altered disturbance regimes; (4) invasive species; and (5) localized impacts. For each threat, workshop participants identified science and information needs, including database availability, research priorities, and modeling and mapping needs. Grouping species by habitat and shared threats can make the SSA process and other planning processes for conservation of at-risk species worldwide more efficient and useful. We found a combination of literature review and structured discussion effective for identifying the scientific information and analysis needed to support the development of multiple SSAs. Article impact statement: Species status assessments can be improved by an ecosystem-based approach that groups imperiled species by shared habitats and threats. 相似文献
77.
Thomas Artiss Wesley M. Hochachka Kathy Martin 《Behavioral ecology and sociobiology》1999,46(6):429-434
For several species of birds, high rates of male vigilance are correlated with high rates of female foraging. This relationship
is thought to ultimately result in higher reproductive success for females paired with highly vigilant males. However, previous
research has not examined the behavioural mechanism that produces the correlation between male vigilance and rates of female
foraging. Foraging females may take advantage of vigilance that males are using for other purposes. Alternatively, the purpose
of male vigilance may be to increase females' ability to forage. We examined these alternatives by testing whether vigilance
preceded or followed bouts of female foraging more often than would occur by chance alone, using simultaneous behaviour observations
of pre-incubation pairs of white-tailed ptarmigan (Lagopus leucurus). Our results indicate that each member of a pair may influence the behaviour of the other. Females were more likely to initiate
foraging bouts after males became vigilant than if their mate remained non-vigilant. Moreover, non-vigilant males were more
likely to become vigilant if their mate was foraging than if she was engaged in some other activity. Despite the possibility
that a sexual conflict exists as each member of a pair attempts to maximize its fitness, both sexes behave as though a major
role of male vigilance is to enhance female foraging opportunities.
Received: 3 May 1999 / Received in revised form: 14 June 1999 / Accepted: 16 June 1999 相似文献
78.
Julie Ann Schultz Schiro Klaus J. Meyer-Arendt Sherry K. Schneider 《Journal of Coastal Conservation》2017,21(1):63-83
The yearly influx of Sargassum onto the beaches of northwest Florida is considered a nuisance to some and a necessity to others. In Pensacola Beach, the Santa Rosa Island Authority rakes the wrack with mechanical beach cleaners to improve the aesthetic quality for beachgoers. The purpose of this study was three-fold: to evaluate the local faunal use of Sargassum wrack, to gauge public perception of Sargassum on the beach, and to test whether public perception of the beauty of the beach, the necessity of raking, and the likelihood of visiting could be influenced by a simple educational sign. A two-part methodology consisted of 1) systematic observation of faunal use, and 2) interviews of 200 beachgoers via a detailed pre-post/post only public use survey. Results showed that 11 of the 22 species of shorebirds documented, including two uncommon migrants, were observed using Sargassum wrack to forage, rest, and hide. Public survey results demonstrated that although beachgoers generally considered themselves to be “ecofriendly”, their perceptions of Sargassum wrack can be positively influenced through environmental education such as informative signage on the beach. In conclusion, Sargassum wrack provides valuable additional habitat to shorebirds and other critters, and that leaving the beach wrack to naturally become part of the ecosystem would not deter most beachgoers (70%) from visiting Pensacola Beach. This research contributes valuable information to coastal managers and other stakeholders for improved ecosystem protection and management. 相似文献
79.
Robert Gifford Leila Scannell Christine Kormos Lidia Smolova Anders Biel Stefan Boncu Victor Corral Hartmut Güntherf Kazunori Hanyu Donald Hine Florian G. Kaiser Kalevi Korpela Luisa Marie Lima Angela G. Mertig Ricardo Garcia Mira Gabriel Moser Paola Passafaro José Q. Pinheiro Sunil Saini Toshihiko Sako Elena Sautkina Yannick Savina Peter Schmuck Wesley Schultz Karin Sobeck Eva-Lotta Sundblad David Uzzell 《Journal of environmental psychology》2009
The personal assessments of the current and expected future state of the environment by 3232 community respondents in 18 nations were investigated at the local, national, and global spatial levels. These assessments were compared to a ranking of each country's environmental quality by an expert panel. Temporal pessimism (“things will get worse”) was found in the assessments at all three spatial levels. Spatial optimism bias (“things are better here than there”) was found in the assessments of current environmental conditions in 15 of 18 countries, but not in the assessments of the future. All countries except one exhibited temporal pessimism, but significant differences between them were common. Evaluations of current environmental conditions also differed by country. Citizens' assessments of current conditions, and the degree of comparative optimism, were strongly correlated with the expert panel's assessments of national environmental quality. Aside from the value of understanding global trends in environmental assessments, the results have important implications for environmental policy and risk management strategies. 相似文献
80.
Dispersal Behavior and Its Implications for Reserve Design in a Rare Oregon Butterfly 总被引:10,自引:0,他引:10
Cheryl B. Schultz 《Conservation biology》1998,12(2):284-292