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排序方式: 共有294条查询结果,搜索用时 15 毫秒
231.
Scott C. Burgess Kate Osborne Bianca Sfiligoj Hugh Sweatman 《Environmental monitoring and assessment》2010,168(1-4):345-351
Seasonal variations in the concentrations of groundwater with respect to arsenic, lead, cadmium and aluminium has been studied in Dhemaji district of Assam, India. The water samples were collected from 20 different sites in both dry and wet seasons. The metals were analysed by using atomic absorption spectrometer, Perkin Elmer AAnalyst 200 model. The concentrations of aluminium, lead and cadmium in groundwater were found to be significantly elevated. High concentrations of all the metals were recorded in the dry season than in the wet season. Univariate statistics along with skewness, kurtosis and confidence limit have been calculated for both the seasons to test the distribution normality for each metal. Statistical analyses of the data reveal non-uniform distribution of the metals in the area. The metal contamination of groundwater in the district follows the trend Al > Pb > Cd > As in both the seasons. 相似文献
232.
Melnyk LJ McCombs M Brown GG Raymer J Nishioka M Buehler S Freeman N Michael LC 《Journal of environmental monitoring : JEM》2012,14(1):85-93
An observational field study was conducted to assess the feasibility of a community duplicate diet collection method; a dietary monitoring tool that is population-based. The purpose was to establish an alternative procedure to duplicate diet sampling that would be more efficient for a large, defined population, e.g., in the National Children's Study (NCS). Questionnaire data and food samples were collected in a residence so as not to lose the important component of storage, preparation, and handling in a contaminated microenvironment. The participants included nine Hispanic women of child bearing age living in Apopka, FL, USA. Foods highly consumed by Hispanic women were identified based on national food frequency questionnaires and prioritized by permethrin residue concentrations as measured for the Pesticide Data Program. Participants filled out questionnaires to determine if highly consumed foods were commonly eaten by them and to assess the collection protocol for the food samples. Measureable levels of permethrin were found in 54% of the samples. Questionnaire responses indicated that the collection of the community duplicate diet was feasible for a defined population. 相似文献
233.
Peter Chin Christopher DeLuca Cheryl Poth Ingrid Chadwick Nancy Hutchinson Hugh Munby 《Safety Science》2010,48(5):570-579
Work-related injury rates for Canadian youth (ages 15–24) are alarmingly high compared to adult workers even though youth are less likely to be performing hazardous jobs. This paper reports on a document analysis of youth workplace safety education initiatives sponsored by national and provincial/territorial governmental and non-governmental agencies. Web-based documents were analyzed through the theoretical lens of self-advocacy. The self-advocacy framework highlights how youth can be agentic in altering high-risk workplaces by publicly articulating their own interests, needs, and rights (Test et al., 2005); thus, self-advocacy is a critical component in studying educational programs for youth safety. The analysis revealed that instruction on workplace safety identifies safety issues to workers and tells youth to work safely but does little to promote self-advocacy in young workers. 相似文献
234.
Helen Mills Poulos Rachael S. Freeman Jennifer M. Karberg Karen C. Beattie Danielle I. ODell Kelly A. Omand 《Environmental management》2020,65(1):111-121
Coastal sandplains provide habitat for a suite of rare and endangered plant and wildlife species in the northeastern United States. These early successional plant communities were maintained by natural and anthropogenic disturbances including salt spray, fire, and livestock grazing, but over the last 150 years, a decrease in anthropogenic disturbance frequency and intensity has resulted in a shift towards woody shrub dominance at the expense of herbaceous taxa. This study quantified the effects of more than a decade of dormant season disturbance-based vegetation management (mowing and prescribed fire) on coastal sandplain plant community composition on Nantucket Island, Massachusetts, USA. We used time-series plant cover data from two similar sites to evaluate the effectiveness of disturbance management for restoring herbaceous species cover and reducing woody shrub dominance. Our results indicate that applying management outside of the peak of the growing season has not been effective in maintaining or increasing the cover of herbaceous species. While management activities resulted in significant (P < 0.01) increases in herbaceous species immediately after treatment, woody species recolonized and dominated treated sites within 3-years post treatment at the expense of graminoids and forbs. These results highlight the difficulties associated with directing ecological succession using disturbance-based management to maintain rare, herbaceous species in coastal sandplain systems that were once a prevalent landscape component under historically chronic anthropogenic disturbance. Further experimentation with growing season disturbance-based management and different combinations of management techniques could provide insights into management alternatives for maintaining herbaceous conservation targets in coastal sandplains. 相似文献
235.
Richard A. Valdez Colleen Cunningham Ali Effati Deborah L. Freeman 《Journal of the American Water Resources Association》2023,59(5):1084-1098
Warmwater fish habitat in the San Juan River of the southwestern United States has been reduced by over 30% as a result of water depletion, reservoir inundation, and cold-water dam releases combined with drought-related changes in hydrology. This reduction and a suite of other factors have contributed to declines in native fish populations including the federally endangered Colorado Pikeminnow (Ptychocheilus lucius) and Razorback Sucker (Xyrauchen texanus). Conservation efforts for these species include determining flow needs; protecting, managing, and augmenting habitats; and stocking hatchery fish. But the young of stocked fish have low survival due largely to a paucity of nursery habitat not being reformed and maintained under current conditions. Flow recommendations for Navajo Dam releases designed to mimic the river's natural hydrograph have not been met due to water shortages, and the desired outcomes of increased channel complexity and enhanced fish habitat have not been observed. Forecasted hydrology that includes ongoing drought shows that achieving the flow targets through further dam reoperations is unlikely. Mechanical construction of early life-stage habitats is a highly recommended complement to flow management for offsetting the effects of flow reduction and habitat loss. Habitats with features that are effective and resilient under a range of flows are important in counterbalancing the effects of climate change. 相似文献
236.
Dust monitoring using sticky pads was popularised in the 1980s. The discolouration caused by dust adhering to white adhesive
material was measured with a smoke stain reflectometer. This loss of reflectance was expressed as the percentage effective
area coverage (EAC%) per day. EAC% can be used as a measure of nuisance caused by dust. EAC% may also be measured with a hand-held
Sticky Pad Reader (SPR). Sticky pads can be mounted on flat or cylindrical surfaces to measure dust by deposition or in flux.
An alternative method was developed in the 1990s that measured total dust coverage using computer-based scanning. DustScan
used a transparent adhesive film wrapped around a vertical cylinder with magnetic north marked. The sticky pad was sealed
with another transparent sheet before scanning at 50 dots per inch (dpi). Dust levels were assessed by comparing the grey-scale
values of pixels in the exposed area with an unexposed reference area. Insects and other extraneous material could be ‘masked
out’ from the computer analysis. Dust coverage was expressed as percentage absolute area coverage (AAC%). DustScan has subsequently
been developed commercially. A limited trial indicated that monitoring periods of 7–14 days were preferred to avoid dust saturation
of the sticky pad. A method for calculating EAC% has been developed and shown to have a high degree of correspondence with
an SPR. A trial for the Minerals Industry Research Organisation (MIRO) made comparisons between DustScan and other dust monitoring
methods. Dust nuisance limits based on AAC% and EAC% are proposed.par 相似文献
237.
238.
Controlling range expansion in habitat networks by adaptively targeting source populations 下载免费PDF全文
Karlo Hock Nicholas H. Wolff Roger Beeden Jessica Hoey Scott A. Condie Kenneth R. N. Anthony Hugh P. Possingham Peter J. Mumby 《Conservation biology》2016,30(4):856-866
Controlling the spread of invasive species, pests, and pathogens is often logistically limited to interventions that target specific locations at specific periods. However, in complex, highly connected systems, such as marine environments connected by ocean currents, populations spread dynamically in both space and time via transient connectivity links. This results in nondeterministic future distributions of species in which local populations emerge dynamically and concurrently over a large area. The challenge, therefore, is to choose intervention locations that will maximize the effectiveness of the control efforts. We propose a novel method to manage dynamic species invasions and outbreaks that identifies the intervention locations most likely to curtail population expansion by selectively targeting local populations most likely to expand their future range. Critically, at any point during the development of the invasion or outbreak, the method identifies the local intervention that maximizes the long‐term benefit across the ecosystem by restricting species’ potential to spread. In so doing, the method adaptively selects the intervention targets under dynamically changing circumstances. To illustrate the effectiveness of the method we applied it to controlling the spread of crown‐of‐thorns starfish (Acanthaster sp.) outbreaks across Australia's Great Barrier Reef. Application of our method resulted in an 18‐fold relative improvement in management outcomes compared with a random targeting of reefs in putative starfish control scenarios. Although we focused on applying the method to reducing the spread of an unwanted species, it can also be used to facilitate the spread of desirable species through connectivity networks. For example, the method could be used to select those fragments of habitat most likely to rebuild a population if they were sufficiently well protected. 相似文献
239.
Erik Meijaard Marcel Cardillo Emily M. Meijaard Hugh P. Possingham 《Conservation biology》2015,29(3):920-925
We investigated whether the impact of conservation science is greater for research conducted in countries with more pressing conservation problems. We quantified research impact for 231 countries based on 2 citation metrics (mean cites per paper and h index) and fitted models predicting research impact based on number of threatened bird and mammal species (as a measure of conservation importance of a country) and a range of demographic variables. Citation rates of conservation research increased as a country's conservation need increased and as human population, quality of governance, and wealth increased. Even after accounting for these factors, citation rates among regions and countries within regions varied significantly. The conservation research community needs to consider ways to begin addressing the entrenched disadvantages some countries have when it comes to initiating projects and producing high‐quality research. 相似文献
240.
Cerveny LK Blahna DJ Stern MJ Mortimer MJ Predmore SA Freeman J 《Environmental management》2011,48(3):644-657
U.S. Forest Service managers are required to incorporate social and biophysical science information in planning and environmental
analysis. The use of science is mandated by the National Environmental Policy Act, the National Forest Management Act, and
U.S. Forest Service planning rules. Despite the agency’s emphasis on ‘science-based’ decision-making, little is known about
how science is actually used in recreation planning and management. This study investigated the perceptions of Forest Service
interdisciplinary (ID) team leaders for 106 NEPA projects dealing with recreation and travel management between 2005 and 2008.
Our survey data show how managers rate the importance of social and biophysical science compared to other potential ‘success
factors’ in NEPA assessments. We also explore how team leaders value and use multi-disciplinary tools for recreation-related
assessments. Results suggest that managers employ a variety of recreation planning tools in NEPA projects, but there appears
to be no common understanding or approach for how or when these tools are incorporated. The Recreation Opportunity Spectrum
(ROS) was the most frequently used planning tool, but the Visitor Experience and Resource Protection (VERP) framework was
the most consistently valued tool by those who used it. We recommend further evaluation of the strengths and weaknesses of
each planning tool and future development of procedures to select appropriate planning tools for use in recreation-related
NEPA assessments. 相似文献