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461.
Australia's Murray–Darling basin (MDB) water plan is an ambitious attempt to balance ecological, social and economic benefits, where a key aspect of the reform process has been recovery of water for environmental use. This paper focuses on a set of initiatives established by a local non-governmental organisation and an Indigenous community designed to engage with local values and priorities and incorporate them into this complex river basin governance system. Contrary to expectations that local and basin-scale interests and outcomes will diverge, the case studies reveal the ability for local groups to collaboratively manage both land and water resources to achieve locally important outcomes, and contribute to basin-scale outcomes. The analysis also highlights a progressive style of community-based environmental management for water management that utilises multiple institutional arrangements and planning pathways to protect the values that are important to local communities, and to nest those values within the broader effort to sustainably manage the basin's water resources.  相似文献   
462.
While climate change adaptation policy has tended to focus on planned adaptation interventions, in many vulnerable communities, adaptation will consist of autonomous, “unplanned” actions by individuals who are responding to multiple simultaneous sources of change. Their actions are likely not only to affect their own future vulnerability, but, through changes in livelihoods and resource use, the vulnerability of their community and resource base. In this paper, we document the autonomous changes to livelihood strategies adopted by smallholder coffee farmers in four Mesoamerican countries (Mexico, Guatemala, Honduras, and Costa Rica). Our aim is to gain insight into the process of autonomous adaptation by proxy: through an assessment of how farmers explain their choices in relation to distinct stressors; and an understanding of the set of choices available to farmers. We find that climatic stress is a feature in decision making, but not the dominant driver. Nevertheless, the farmers in our sample are evidently flexible, adaptive, and experimental in relation to changing circumstances. Whether their autonomous responses to diverse stressors will result in a reduction in risk over time may well depend on the extent to which policy, agricultural research, and rural investments build on the inherent logic of these strategies.  相似文献   
463.
Climate change is expected to cause shifts in species distributions worldwide, threatening their viability due to range reductions and altering their representation in protected areas. Biodiversity hotspots might be particularly vulnerable to climate change because they hold large numbers of species with small ranges which could contract even further as species track their optimal habitat. In this study, we assessed the extent to which climate change could cause distribution shifts in threatened and range-restricted birds in Colombia, a megadiverse region that includes the Tropical Andes and Tumbes-Choco-Magdalena hotspots. To evaluate how climate change might influence species in this region, we developed species distribution models using MAXENT. Species are projected to lose on average between 33 and 43 % of their total range under future climate, and up to 18 species may lose their climatically suitable range completely. Species whose suitable climate is projected to disappear occur in mountainous regions, particularly isolated ranges such as the Sierra Nevada de Santa Marta. Depending on the representation target considered, between 46 and 96 % of the species evaluated may be adequately represented in protected areas. In the future, the fraction of species potentially adequately represented is projected to decline to 30–95 %. Additional protected areas may help to retain representativeness of protected areas, but monitoring of species projected to have the largest potential declines in range size will be necessary to assess the need of implementing active management strategies to counteract the effects of climate change.  相似文献   
464.
The impact of ship emissions on air quality in Alaska National Parks and Wilderness Areas was investigated using the Weather Research and Forecasting model inline coupled with chemistry (WRF/Chem). The visibility and deposition of atmospheric contaminants was analyzed for the length of the 2006 tourist season. WRF/Chem reproduced the meteorological situation well. It seems to have captured the temporal behavior of aerosol concentrations when compared with the few data available. Air quality follows certain predetermined patterns associated with local meteorological conditions and ship emissions. Ship emissions have maximum impacts in Prince William Sound where topography and decaying lows trap pollutants. Along sea-lanes and adjacent coastal areas, NOx, SO2, O3, PAN, HNO3, and PM2.5 increase up to 650 pptv, 325 pptv, 900 pptv, 18 pptv, 10 pptv, and 100 ng m?3. Some of these increases are significant (95% confidence). Enhanced particulate matter concentrations from ship emissions reduce visibility up to 30% in Prince William Sound and 5–25% along sea-lanes.  相似文献   
465.
In a field study among 241 shop assistants and their 59 supervisors in fashion chain stores in Mainland China and Hong Kong, we found a negative relationship between emotional exhaustion and four indicators of job performance (overall performance, emotional display, OCB‐O, and OCB‐I) when employees perceived high levels of distributive justice in the exchange relationship with the organization, whereas emotional exhaustion was unrelated to any of these performance types when employees perceived low levels of distributive justice. In addition, this negative two‐way interaction effect of emotional exhaustion by distributive justice on job performance was buffered when employees were high on positive affect and intensified when they were low on positive affect. We used the conservation of resources (COR) theory, the attribution model of justice, and the broaden‐and‐build theory of positive emotions to clarify and discuss the moderating roles of distributive justice and positive affect in the relationship between emotional exhaustion and job performance. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   
466.
Vortices could play an important role in the occurrence of certain biological phenomena, such as the massive proliferation of harmful algae in bodies of water. Many measures exist to detect vortices in fluids, but little is known about the stochastic behavior of these quantities with data that contain statistical noise. Consequently they do not provide control over the probability of false positives and give little information about the risk of false negatives. Obtaining such control requires a statistical testing procedure. In this paper, we develop a test for vortices in random current fields using only the directions of the current observed at points on a regular grid. We construct a change-point test for spatially ordered angular data to detect the presence of a local vortex. A global vortex detection procedure based on this test is developed and applied to a data set from a lagoon located in the south of France. It is shown that this procedure can detect the presence of multiple vortices with good accuracy.  相似文献   
467.
468.
This paper presents the application of three publicly available biota dose assessment models (the ERICA Tool, R&D128/SP1a and RESRAD-BIOTA) to an assessment of the Drigg coastal sand dunes. Using measured 90Sr, 99Tc, 137Cs, 238Pu, 239+240Pu and 241Am activity concentrations in sand dune soil, activity concentration and dose rate predictions are made for a range of organisms including amphibians, birds, invertebrates, mammals, reptiles, plants and fungi. Predicted biota activity concentrations are compared to measured data where available. The main source of variability in the model predictions is the transfer parameters used and it is concluded that developing the available transfer databases should be a focus of future research effort. The value of taking an informed user approach to investigate the way in which models may be expected to be applied in practice is highlighted and a strategy for the future development of intercomparison exercises is presented.  相似文献   
469.
In this study, we examined how honeybees coped with successive tasks of colour discrimination with conflicting demands. Free-flying honeybees (Apis mellifera) were trained on tasks in which they had to choose one of three colours to obtain a reward of sugar water. In acquisition, the bees learned this task in about four trials of training. Colour memory was retained after 24-h delay in an unrewarded retention test. Integration experiments were then conducted in which the bees had to learn two successive tasks of colour discrimination with conflicting demands, task 1 for 20 trials and task 2 for ten trials. In task 1, one of three colours provided sugar water while the other two provided tap water, while in task 2 a different colour provided the reward. The bees were given unrewarded tests immediately after training on task 2 and then re-tested after 10 min, 22 h (circadian time of the start of task 1 training), or 24 h (circadian time of the end of task 2 training). Bees strongly preferred the rewarded colour for task 2 on immediate testing and after 10-min delay. After 22-h delay, they switched their preference to the rewarded colour for task 1. But after 24-h delay, the bees again strongly preferred the rewarded colour for task 2. Further tests at a number of delays between 0 and 22 h revealed a sigmoidal pattern of rise in the preference for the task 1 colour. We conclude that circadian time modulates the retrieval of colour memories in honeybees, even when all the training took place in a single day.  相似文献   
470.
Wang S  Mulligan CN 《Chemosphere》2009,74(2):274-279
Arsenic and heavy metal mobilization from mine tailings is an issue of concern as it might pose potential groundwater or ecological risks. Increasing attention recently has been focused on the effects of natural organic matter on the mobility behavior of the toxicants in the environment. Column experiments were carried out in this research study to evaluate the feasibility of using humic acid (HA) to mobilize arsenic and heavy metals (i.e., Cu, Pb and Zn) from an oxidized Pb-Zn mine tailings sample collected from Bathurst, New Brunswick, Canada. Capillary electrophoresis analyses indicated that arsenate [As(V)] was the only extractable arsenic species in the mine tailings and the addition of HA at pH 11 did not incur the oxidation-reduction or methylation reactions of arsenic. A 0.1% HA solution with an initial pH adjusted to 11 was selected as the flushing solution, while distilled water (initial pH adjusted to 11) was used as the control to account for the mobilization of arsenic and the heavy metals by physical mixing and the effect of pH. It was found that the HA could significantly enhance the mobilization of arsenic and heavy metals simultaneously from the mine tailings. After a 70-pore-volume-flushing, the mobilization of arsenic, copper, lead and zinc reached 97, 35, 838 and 224 mg kg(-1), respectively. The mobilization of arsenic and the heavy metals was found to be positively correlated with the mobilization of Fe in the presence of the HA. Moreover, the mobilization of arsenic was also correlated well with that of the heavy metals. The mobilization of co-existing metals to some extent might enhance arsenic mobilization in the presence of the HA by helping incorporate it into soluble aqueous organic complexes through metal-bridging mechanisms. Use of HA in arsenic and heavy metal remediation may be developed as an environmentally benign and possible effective remedial option to reduce and avoid further contamination.  相似文献   
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