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41.
Sediment-associated hydrocarbons can pose a risk to wildlife that rely on benthic marine food webs. We measured hydrocarbons in sediments from the habitat of protected sea otters in coastal British Columbia, Canada. Alkane concentrations were dominated by higher odd-chain n-alkanes at all sites, indicating terrestrial plant inputs. While remote sites were dominated by petrogenic polycyclic aromatic hydrocarbons (PAHs), small harbour sites within sea otter habitat and sites from an urban reference area reflected weathered petroleum and biomass and fossil fuel combustion. The partitioning of hydrocarbons between sediments and adjacent food webs provides an important exposure route for sea otters, as they consume ∼25% of their body weight per day in benthic invertebrates. Thus, exceedences of PAH sediment quality guidelines designed to protect aquatic biota at 20% of the sites in sea otter habitat suggest that sea otters are vulnerable to hydrocarbon contamination even in the absence of catastrophic oil spills.  相似文献   
42.
Pair-wise preference experiments were used to reveal predator discrimination by four tit species wintering in the Czech Republic. The reactions of the tits to a more dangerous predator (sparrowhawk) and a less dangerous (kestrel) one were compared. The number of visits to a feeder with a predator present expressed the perceived dangerousness of the predator. The tits' behaviour towards the feeders was in agreement with predictions, according to dynamic risk assessment theory. The presence of any predator at the feeder lowered the number of visits to the feeder. Similarly, the tits were judged to have evaluated the sparrowhawk as being more dangerous than the kestrel, as its presence lowered the number of arrivals more than did the kestrel. The duration of stay and number of pecks of individual birds were also used as measures of predator dangerousness. The results not only confirm that tits behave according to dynamic risk assessment theory, but also show the exceptional suitability of preference experiments for the research of predator differentiation and evaluation.  相似文献   
43.
44.
Antarctic krill, Euphausia superba, is a keystone species of the Antarctic ecosystem. A fishery for krill may compete with land-based predators (penguins and seals), particularly during the breeding season. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is moving towards management in small scale units. The management models specify predation and fishing mortality as space and time dependent but do not yet include non-predation natural mortality. Krill are known to be highly susceptible to ultraviolet radiation (UV) but there are limited empirical data. We develop a model for krill mortality caused by UV and parameterize and assess it by comparison with experimental data. The analysis allows us to identify key parameters that should be measured in future experiments and also leads to suggestions about modification of experimental procedure. We illustrate the method for krill found in the Livingston Island area and show that (a) it is possible to estimate the component of natural mortality due to UV-induced damage and (b) that cohorts born in 1979, 1984, or 1997 have different survival in the first 5 years of life, associated with differential UV exposure. In particular, those born in 1997 may have experienced as much as 10% lower survival than those born in 1979. The method developed here allows a potentially important source of krill mortality to be incorporated into the management models and suggests key experiments and field work in the future.  相似文献   
45.
Global biodiversity indices are used to measure environmental change and progress toward conservation goals, yet few indices have been evaluated comprehensively for their capacity to detect trends of interest, such as declines in threatened species or ecosystem function. Using a structured approach based on decision science, we qualitatively evaluated 9 indices commonly used to track biodiversity at global and regional scales against 5 criteria relating to objectives, design, behavior, incorporation of uncertainty, and constraints (e.g., costs and data availability). Evaluation was based on reference literature for indices available at the time of assessment. We identified 4 key gaps in indices assessed: pathways to achieving goals (means objectives) were not always clear or relevant to desired outcomes (fundamental objectives); index testing and understanding of expected behavior was often lacking; uncertainty was seldom acknowledged or accounted for; and costs of implementation were seldom considered. These gaps may render indices inadequate in certain decision-making contexts and are problematic for indices linked with biodiversity targets and sustainability goals. Ensuring that index objectives are clear and their design is underpinned by a model of relevant processes are crucial in addressing the gaps identified by our assessment. Uptake and productive use of indices will be improved if index performance is tested rigorously and assumptions and uncertainties are clearly communicated to end users. This will increase index accuracy and value in tracking biodiversity change and supporting national and global policy decisions, such as the post-2020 global biodiversity framework of the Convention on Biological Diversity.  相似文献   
46.
Biochar is increasingly been used as a soil amendment to improve water-holding capacity, reduce nutrient leaching, increase soil pH, and also as a means to reduce contamination through sorption of heavy metals or organic pollutants. The sorption behavior of three phenylurea herbicides (monuron, diuron and linuron) on five biochars (Enhanced Biochar, Hog Waste, Turkey Litter, Walnut Shell and Wood Feedstock) and an agricultural soil (Yolo silt loam) was investigated using a batch equilibration method. Sorption isotherms of herbicides to biochars were well described by the Freundlich model (R2 = 0.93–0.97). The adsorption KF values ranged from 6.94 to 1306.95 mg kg?1 and indicated the sorption of herbicides in the biochars and Yolo soil was in the sequence of linuron > diuron > monuron and walnut shell biochar > wood feedstock biochar > turkey litter biochar > enhanced biochar > hog waste biochar > Yolo soil. These data show that sorption of herbicides to biochar can have both positive (reduced off-site transport) and negative (reduced herbicide efficacy) implications and specific biochar properties, such as H/C ratio and surface area, should be considered together with soil type, agriculture chemical and climate condition in biochar application to agricultural soil to optimize the system for both agricultural and environmental benefits.  相似文献   
47.
To date analyses of media climate change constructions have mostly focused on coverage in western newspapers. Consideration of coverage in developing countries, and analyses of media constructions alongside local understandings of climate change are comparatively rare. This article provides an analysis of the construction of climate change on Nepalese radio and lay constructions of environment and climate change within the country. Data from a radio program and six focus groups are analyzed. Analysis of the radio program indicated that climate change was portrayed as a certain reality with national impacts caused by the actions of the West. While climate change dominated the radio headlines, in focus groups local environmental problems received far more attention. The paper aims to both inform directions for future climate change communication in Nepal and the wider research agenda.  相似文献   
48.
In 2004–05, Niger suffered a food crisis during which global attention focused on high levels of acute malnutrition among children. In response, decentralised emergency nutrition programmes were introduced into much of southern Niger. Child malnutrition, however, is a chronic problem and its links with food production and household food security are complex. This qualitative, anthropological study investigates pathways by which children are rendered vulnerable in the context of a nutritional 'emergency'. It focuses on household-level decisions that determine resource allocation and childcare practices in order to explain why practices apparently detrimental to children's health persist. Risk aversion, the need to maintain self-identity and status, and constrained decision making result in a failure to invest extra necessary resources ingrowth-faltering children. Understanding and responding to the social context of child malnutrition will help humanitarian workers to integrate their efforts more effectively with longer-term development programmes aimed at improving livelihood security.  相似文献   
49.
Organizational efforts to improve team effectiveness in crisis situations primarily have focused on team training initiatives and, to a lesser degree, on staffing teams with respect to members' ability, experience, and functional backgrounds. Largely neglected in these efforts is the emotional component of crises and, correspondingly, the notion of staffing teams with consideration for their affective makeup. To address this void, we examined the impact of team member dispositional positive affect (PA) on team crisis effectiveness and the role of felt negative emotion in transmitting that influence. A study of 21 nuclear power plant crews engaged in crisis training simulations revealed that homogeneity in PA, but not mean‐level PA, was associated with greater team effectiveness. Mediation analysis suggested that homogeneity in PA leads to greater team effectiveness by reducing the amount of negative emotions that team members experience during crises. Furthermore, homogeneity in PA compensated for lower mean‐level PA in predicting effectiveness. Discussion focuses on the implications of these findings for understanding and further exploring the importance of affective factors and especially team affective composition in team crisis performance. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
50.
To reduce greenhouse gas (GHG) emissions and help mitigate climate change, urban water systems need to be adapted so that electrical energy use is minimised. In this study, energy data from 2011 was used to quantify energy use in China’s urban water supply sector. The objective was to calculate the energy co-benefits of urban water conservation policies and compare energy use between China and other countries. The study investigated influencing factors with the aim of informing the development of energy efficient urban water infrastructure. The average energy use per cubic metre and per capita for urban water supply in China in 2011 was 0.29 kWh/m3 and 33.2 kWh/cap year, respectively. Total GHG emissions associated with energy use in the urban water supply sector were 7.63 MtCO2e, or carbon dioxide equivalent. Calculations using these indicators showed significant energy savings could result from water conservation measures. A comparison between provinces of China showed a direct correlation between energy intensity of urban water supply and the population served per unit length of pipe. This may imply energy and emission intensity can be reduced if more densely populated areas are supplied by a corresponding pipe density, rather than by a low-density network operating at higher flow rates. This study also found that while the percentage of electrical energy used for urban water supply tended to increase with the percentage of population served, this increase was slower where water supply was more energy efficient and where a larger percentage of population was already supplied.  相似文献   
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