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251.
252.
National Pollution Discharge Elimination Permit (NPDES)-driven effluent toxicity tests using Ceriodaphnia dubia and fathead minnows were conducted for more than 20 years to assess and monitor the effects of wastewaters at the United
States (U.S.) Department of Energy Y-12 National Security Complex (Y-12 Complex) in Oak Ridge, Tennessee. Toxicity testing
was also conducted on water samples from East Fork Poplar Creek (EFPC), the wastewater receiving stream, as part of a comprehensive
biological monitoring and assessment program. In this paper, we evaluate the roles of this long-term toxicity assessment and
monitoring program in the management and ecological recovery of EFPC. Effluent toxicity testing, associated toxicant evaluation
studies, and ambient toxicity monitoring were instrumental in identifying toxicant sources at the Y-12 Complex, guiding modifications
to wastewater treatment procedures, and assessing the success of various pollution-abatement actions. The elimination of untreated
wastewater discharges, the dechlorination of remaining wastewater streams, and the implementation of flow management at the
stream headwaters were the primary actions associated with significant reductions in the toxicity of stream water in the upper
reaches of EFPC from the late 1980s through mid 1990s. Through time, as regulatory requirements changed and water quality
improved, emphasis shifted from comprehensive toxicity assessments to more focused toxicity monitoring efforts. Ambient toxicity
testing with C. dubia and fathead minnows was supplemented with less-standardized but more sensitive alternative laboratory toxicity tests and
in situ bioassays. The Y-12 Complex biological monitoring experience demonstrates the value of toxicity studies to the management
of a wastewater receiving stream. 相似文献
253.
We review long-term changes that have occurred in factors affecting water quality in East Fork Poplar Creek (EFPC; in East
Tennessee) over a nearly 25-year monitoring period. Historically, the stream has received wastewaters and pollutants from
a major United States Department of Energy (DOE) facility on the headwaters of the stream. Early in the monitoring program,
EFPC was perturbed chemically, especially within its headwaters; evidence of this perturbation extended downstream for many
kilometers. The magnitude of this perturbation, and the concentrations of many biologically significant water-quality factors,
has lessened substantially through time. The changes in water-quality factors resulted from a large number of operational
changes and remedial actions implemented at the DOE facility. Chief among these were consolidation and elimination of many
effluents, elimination of an unlined settling/flow equalization basin, reduction in amount of blow-down from cooling tower
operations, dechlorination of effluents, and implementation of flow augmentation. Although many water-quality characteristics
in upper EFPC have become more similar to those of reference streams, conditions remain far from pristine. Nutrient enrichment
may be one of the more challenging problems remaining before further biological improvements occur. 相似文献
254.
Quantifying the influence of environmental and water conservation attitudes on household end use water consumption 总被引:3,自引:0,他引:3
Willis RM Stewart RA Panuwatwanich K Williams PR Hollingsworth AL 《Journal of environmental management》2011,92(8):1996-2009
Within the research field of urban water demand management, understanding the link between environmental and water conservation attitudes and observed end use water consumption has been limited. Through a mixed method research design incorporating field-based smart metering technology and questionnaire surveys, this paper reveals the relationship between environmental and water conservation attitudes and a domestic water end use break down for 132 detached households located in Gold Coast city, Australia. Using confirmatory factor analysis, attitudinal factors were developed and refined; households were then categorised based on these factors through cluster analysis technique. Results indicated that residents with very positive environmental and water conservation attitudes consumed significantly less water in total and across the behaviourally influenced end uses of shower, clothes washer, irrigation and tap, than those with moderately positive attitudinal concern. The paper concluded with implications for urban water demand management planning, policy and practice. 相似文献
255.
R. Terry Bowyer Janet L. Rachlow Kelley M. Stewart Victor Van Ballenberghe 《Behavioral ecology and sociobiology》2011,65(12):2251-2260
Evidence of female fomentation of male–male aggression as a mechanism of mate choice is rare, especially in mammals. Female
choice of mates in polygynous species may be masked by intense male competition or by males attempting to restrict female
choice. We studied protest moans of female Alaskan moose Alces alces gigas in interior Alaska, USA, from 1987 to 1990, to determine if moans incited male–male aggression. Alaskan moose exhibit a mating
system in which one dominant male (the harem master) herds, defends, courts, and attempts to mate with females in his harem.
Protest moans were given by females only in response to courtship. We hypothesized that if protest moans were related to females
reducing harassment and exercising mate choice, females should give protest moans more frequently when courted by small males
and less often when courted by large males, and that rates of male–male aggression would be elevated following protest moans.
Harems were composed of one large male, with a mean of 4.4 females (median = 3 females); 10% of 132 harems included ≥10 females.
The temporal pattern of protest moans from late August through November was associated with, but tended to lag behind, mating
behavior. The rate of protest moans given by females decreased with increasing size of males courting them. Male–male aggression
was significantly less during periods without protest moans than during periods in which protest moans occurred. These results
indicate that female moose gave protest moans to reduce harassment by smaller males, and assure a mating opportunity with
the most dominant male. Such a subtle mechanism of indirect mate choice by females may occur in other vertebrates in which
choice is limited by a mating system in which male–male combat and male dominance over females reduces opportunities for female
choice. The importance of female choice may be undervalued in studies of sexual selection in mammals. 相似文献
256.
Replicate mass-balanced solutions to Ecopath models describing carbon-based trophic structures and flows were developed for the Lake Ontario offshore food web before and after invasion-induced disruption. The food webs link two pathways of energy and matter flow: the grazing chain (phytoplankton-zooplankton-fish) and the microbial loop (bacteria-protozoans) and include 19 species-groups and three detrital groups. Mass-balance was achieved by using constrained optimization techniques to randomly vary initial estimates of biomass and diet composition. After the invasion, production declined for all trophic levels and species-groups except Chinook salmon. The trophic level (TL) increased for smelt, adult sculpin, adult alewife and Chinook salmon. Changes to ecotrophic efficiencies indicate a reduction in phytoplankton grazing, increased predation pressure on Mysis, adult smelt and alewife and decreased predation pressure on protozoans. Specific resource to consumer TTE changed; increasing for protozoans (8.0-11.5%), Mysis (0.6-1.0%), and Chinook salmon (1.0-2.3%) and other salmonines (0.4-0.5%) and decreasing for zooplankton (20.2-15.1%), prey-fish (9.7-8.8%), and benthos (1.7-0.6%). Direct trophic influences of recent invasive species were low. The synchrony of the decline in PP and species-group production indicates strong bottom-up influence. Mass balance required an increase of two to threefold in lower trophic level biomass and production, confirming a previously observed paradoxical deficit in lower trophic level production. Analysis of food web changes suggest hypotheses that may apply to other similar large pelagic systems including, (1) as pelagic primary productivity declines, overgrazing of zooplankton results in an increase in protozoan production and a loss of trophic transfer efficiency, (2) habitat and food web changes increased Mysis predation on Diporeia and contributed to their recent decline, and (3) production of Chinook salmon, the primary piscivore, was uncoupled from pelagic production processes. This study demonstrates the value of food web models to better understand the impact of invasive species and to develop novel hypotheses concerning trophic influences. 相似文献
257.
Yahya Thamrin Author Vitae Author Vitae Sasha Stewart Author Vitae 《Journal of Safety Research》2010,41(1):59-63
Problem
Young workers are over-represented in injury statistics. In order to develop injury prevention strategies, this study investigated time trends and predictive factors relating to safety skills, confidence, and attitudes.Method
Annual surveys were conducted from 2006-2009 among incoming students at the University of Adelaide. The questions addressed safety training, injury experience, and health and safety perceptions.Results
Time trends in training, perceived safety skills, confidence, and attitudes were not significant. In terms of skills and confidence, the most important correlate was safety training outside of high school (odds ratio = 1.6), especially when repeated, assessed, or in face to face mode. Feeling strongly about safety issues was best predicted by injury experience (OR = 1.7) and gender.Discussion
These results emphasize the value of assessed training, but they are also consistent with published U.S. data, indicating no improvement over time. It is suggested that there be a more integrated approach in safety education, involving schools and workplaces.Impact on industry
By developing an understanding of student safety perceptions and experiences, this research aims to target strategies to reduce the excess injury rate for young workers. Workplaces should be more aware of the limitations of school-based safety education and a more integrated and evidence-based approach should be developed, involving schools and workplaces. 相似文献258.
本文论述了周界入侵探测系统(PIDS)集成方面的问题,涉及PIDS场地网络的各种要素,实现标准化的好处,系统集成的不同模式等,探讨了未来有可能得到更多应用的PIDS集成标准。 相似文献
259.
Sávio S.V. Vianna R. Stewart Cant 《Journal of Loss Prevention in the Process Industries》2010,23(1):3-14
The production of oil and gas is an inherently hazardous task. Therefore it is crucial to provide reliable estimates of the risks involved. The major contributors to the risk level of an offshore installation, for example, arise from accidents involving explosion and fire. Computational Fluid Dynamics (CFD) can be a powerful tool to help with the calculation of accidental explosion scenarios. In this context, the present work suggests a novel implementation of a model based on a modified Porosity Distributed Resistance (MPDR) approach within an unstructured 3D Navier–Stokes solver. The model operates by representing parts of the filtered geometry from the original model through porosity values attributed to an unstructured tetrahedral mesh. Extra resistance terms are added in the momentum equation as well as extra sources of turbulence. Two extra sources of turbulence are modelled. The first of these is due to the shear layers of the non-resolved obstacles, whilst the second is due to the presence of wakes behind the non-resolved obstacles. Results for 2D and 3D test cases are compared against both experimental data and simulations with fully-resolved geometry and good agreement is observed. 相似文献
260.
The purpose of the present study was to establish sonographic markers for prenatal diagnosis of trisomies 13 and 18. Retrospective analysis of sonographic morphology was therefore carried out in seven fetuses with trisomy 13, and 16 fetuses with trisomy 18. Gestational age ranged between 17 and 39 weeks (median 28 weeks). Polyhydramnios and symmetrical growth retardation were present in 14 of 23 fetuses. A cardiac anomaly was diagnosed in all 23 fetuses, the majority representing a ventricular septal defect (n = 8) or double outlet right ventricle (n = 8). Extra-cardiac anomalies were characterized by a high incidence of limb deformities (polydactyly, clenched hands, club feet; n = 15) and omphalocele (n = 7). We conclude that the combined appearance of cardiac and extra-cardiac anomalies should prompt fetal karyotyping. Cardiac anomalies in combination with fetal limb deformities and omphalocele are suspicious for trisomies 13 and 18. 相似文献