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111.
There is concern that visitor-use associated activities, such as bathing, dish washing, wastewater production, and stock animal use near lakes and streams, could cause degradation of water quality in Yosemite National Park. A study was conducted during 2004-2007 to assess patterns in nutrient and Escherichia coli (E. coli) concentrations in the Merced and Tuolumne Rivers and characterize natural background concentrations of nutrients in the park. Results indicated that nutrient and E. coli concentrations were low, even compared to other undeveloped sites in the United States. A multiple linear regression approach was used to model natural background concentrations of nutrients, with basin characteristics as explanatory variables. Modeled nitrogen concentrations increased with elevation, and modeled phosphorus concentrations increased with basin size. Observed concentrations (±uncertainty) were compared to modeled concentrations (±uncertainty) to identify sites that might be impacted by point sources of nutrients, as indicated by large model residuals. Statistically significant differences in observed and modeled concentrations were observed at only a few locations, indicating that most sites were representative of natural background conditions. The empirical modeling approach used in this study can be used to estimate natural background conditions at any point along a study reach in areas minimally impacted by development, and may be useful for setting water-quality standards in many national parks.  相似文献   
112.
Firewood is the basic fuel source in rural Bolivia. A study was conducted in an Andean village of subsistence farmers to investigate human impact on wild firewood species. A total of 114 different fuel species was inventoried during fieldtrips and transect sampling. Specific data on abundance and growth height of wild firewood species were collected in thirty-six transects of 50 ×2 m2. Information on fuel uses of plants was obtained from 13 local Quechua key participants. To appraise the impact of fuel harvest, the extraction impact value (EIV) index was developed. This index takes into account local participants?? appreciation of (1) decreasing plant abundance; (2) regeneration capacity of plants; (3) impact of root harvesting; and (4) quality of firewood. Results suggest that several (sub-)woody plant species are negatively affected by firewood harvesting. We found that anthropogenic pressure, expressed as EIV, covaried with density of firewood species, which could entail higher human pressure on more abundant and/or more accessible species. The apparent negative impact of anthropogenic pressure on populations of wild fuel species is corroborated by our finding that, in addition to altitude, several anthropogenic variables (i.e. site accessibility, cultivation of exotics and burning practices) explain part of the variation in height of firewood species in the surroundings of Apillapampa.  相似文献   
113.
 Honeybees, Apis spp., maintain elevated temperatures inside their nests to accelerate brood development and to facilitate defense against predators. We present an additional defensive function of elevating nest temperature: honeybees generate a brood-comb fever in response to colonial infection by the heat-sensitive pathogen Ascosphaera apis. This response occurs before larvae are killed, suggesting that either honeybee workers detect the infection before symptoms are visible, or that larvae communicate the ingestion of the pathogen. This response is a striking example of convergent evolution between this "superorganism" and other fever-producing animals. Received: 2 September 1999 / Accepted in revised form: 28 February 2000  相似文献   
114.
Urban futures that are more resilient and sustainable require an integrated social–ecological system approach to urban policymaking, planning, management, and governance. In this article, we introduce the Urban Biodiversity and Ecosystem Services (URBES) and the Cities and Biodiversity Outlook (CBO) Projects as new social–ecological contributions to research and practice on emerging urban resilience and ecosystem services. We provide an overview of the projects and present global urbanization trends and their effects on ecosystems and biodiversity, as a context for new knowledge generated in the URBES case-study cities, including Berlin, New York, Rotterdam, Barcelona, and Stockholm. The cities represent contrasting urbanization trends and examples of emerging science–policy linkages for improving urban landscapes for human health and well-being. In addition, we highlight 10 key messages of the global CBO assessment as a knowledge platform for urban leaders to incorporate state-of-the-art science on URBES into decision-making for sustainable and resilient urban development.  相似文献   
115.
Roof rats (Rattus rattus) and deer mice (Peromyscus maniculatus) are occasional pests of nut and tree fruit orchards throughout California and in many other parts of the USA and beyond. In general, the most practical and cost-effective control method for rodents in many agricultural environments is the use of rodenticides (toxic baits), but little or no information exists on the efficacy of current rodenticides in controlling roof rats and deer mice in orchards. Therefore, our goals were to develop an index of rodent activity to monitor efficacy of rodenticides and to subsequently test the efficacy of three California Department of Food and Agriculture rodenticide baits (0.005 % chlorophacinone treated oats, 0.005 % diphacinone treated oats, and 0.005 % diphacinone wax block) to determine their utility for controlling roof rats and deer mice in agricultural orchards. We determined that a general index using the number of roof rat photos taken at a minimum of a 5-min interval was strongly correlated to the minimum number known estimate of roof rats; this approach was used to monitor roof rat and deer mouse populations pre- and post-treatment. Of the baits tested, the 0.005 % diphacinone treated oats was most effective for both species; 0.005 % chlorophacinone grain was completely ineffective against roof rats. Our use of elevated bait stations proved effective at providing bait to target species and should substantially limit access to rodenticides by many non-target species.  相似文献   
116.
Chemical Leasing is a service-oriented business model that shifts the focus from increasing sales volume of chemicals towards a value-added approach. Recent pilot projects have shown the economic benefits of introducing Chemical Leasing business models in a broad range of sectors. A decade after its introduction, the promotion of Chemical Leasing is still predominantly done by the public sector and international organizations. We show in this paper that awareness-raising activities to disseminate information on this innovative business model mainly focus on the economic benefits. We argue that selling Chemical Leasing business models solely on the grounds of economic and ecological considerations falls short of branding it as a corporate social responsibility initiative, which, for this paper, is defined as a stakeholder-oriented concept that extends beyond the organization’s boundaries and is driven by an ethical understanding of the organization’s responsibility for the impact of its business activities. For the analysis of Chemical Leasing business models, we introduce two case studies from the water purification and metal degreasing fields, focusing on employees and local communities as two specific stakeholder groups of the company introducing Chemical Leasing. The paper seeks to demonstrate that Chemical Leasing business models can be branded as a corporate social responsibility initiative by outlining the vast potential of Chemical Leasing to improve occupational health and safety and to strengthen the ability of companies to protect the environment from the adverse effects of the chemicals they apply.  相似文献   
117.
Prenatal diagnosis of Sandhoff disease (infantile onset) at 16 weeks gestation has been made by detection and analysis of N-acetylglucosaminyl-oligosaccharides in amniotic fluid using high performance liquid chromatography. The elution profile for the branched chain oli-gosaccharides was identical with that obtained with neonatal and infantile Sandhoff urine. The concentration of the oligosaccharides in the fluid was 1/100th that of urine but when calculated relative to creatinine the levels were similar. No oligosaccharides were detected in normal control amniotic fluids (10 patients) at a similar gestational age. Based on the levels of the amniotic fluid oligosaccharides and the sensitivity limits of the assay, prenatal diagnosis of patients with the juvenile onset form of the disease may also be possible with this technique.  相似文献   
118.
The diagnosis of congenital nephrosis is difficult during the antepartum period. The combination of an elevated amniotic fluid alpha-fetoprotein, a negative acetylcholinesterase, and a negative ultrasound examination is highly indicative of congenital nephrosis; however, these findings can also be associated with a normal gestation. This is the first report of pathologic confirmation of congenital nephrosis from an in utero fetal kidney biopsy. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
119.
A baseline for a project consists of estimates of annual emissions of greenhouse gases (GHG) for a given time period without implementing the project. A general three-step process for determining the baseline is suggested. The emission reduction of the project is given by the difference between the baseline and the monitored annual emissions. A preferred method, direct measurement of the emission reduction, is possible for some types of projects. Methods for estimating the annual baseline emissions are not necessary for the latter category, and a definition of this project category is suggested. IPCC Guidelines for National GHG Inventories categorise the emission sources so that only direct emissions from consumption of fuel and feedstock are calculated. There are thus no emission factors for indirect emissions (e.g. electricity consumption or km transported) or emission factors that depend on technology only, independent of consumption of fuel and feedstock. Technology-dependent emission factors may thus need to be developed for estimating indirect emissions and multi-project baselines. Consistency should be sought with the IPCC Guidelines when estimating annual baseline emissions and in monitoring project emissions to ensure comparability with the National Inventories.  相似文献   
120.
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