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161.
Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants.  相似文献   
162.
Biodiversity studies that guide agricultural subsidy policy have generally compared farming systems at a single spatial scale: the field. However, diversity patterns vary across spatial scales. Here, we examined the effects of farming system (organic vs. conventional) and position in the field (edge vs. center) on plant species richness in wheat fields at three spatial scales. We quantified alpha-, beta-, and gamma-diversity at the microscale in 800 plots, at the mesoscale in 40 fields, and at the macroscale in three regions using the additive partitioning approach, and evaluated the relative contribution of beta-diversity at each spatial scale to total observed species richness. We found that alpha-, beta-, and gamma-diversity were higher in organic than conventional fields and higher at the field edge than in the field center at all spatial scales. In both farming systems, beta-diversity at the meso- and macroscale explained most of the overall species richness (up to 37% and 25%, respectively), indicating considerable differences in community composition among fields and regions due to environmental heterogeneity. The spatial scale at which beta-diversity contributed the most to overall species richness differed between rare and common species. Total richness of rare species (present in < or = 5% of total samples) was mainly explained by differences in community composition at the meso- and macroscale (up to 27% and 48%, respectively), but only in organic fields. Total richness of common species (present in > or = 25% of total samples) was explained by differences in community composition at the micro- and mesoscale (up to 29% and 47%, respectively), i.e., among plots and fields, independent of farming system. Our results show that organic farming made the greatest contribution to total species richness at the meso (among fields) and macro (among regions) scale due to environmental heterogeneity. Hence, agri-environment schemes should exploit this large-scale contribution of beta-diversity by tailoring schemes at regional scales to maximize dissimilarity between conservation areas using geographic information systems rather than focusing entirely at the classical local-field scale, which is the current practice.  相似文献   
163.
ABSTRACT: Increasing awareness about the problems brought on by urban sprawl has led to proactive measures to guide future development. Such efforts have largely been grouped under the term “Smart Growth.” Although not widely recognized as such, the “smart” in Smart Growth implies an optimization of some quantity or objective while undertaking new forms of urban development. In this study, we define Smart Growth as that development plan that leads to the optimal value of a precisely defined measure identified by a stakeholder or stakeholders. To illustrate a formal, quantitative framework for Smart Growth, this study develops definitions of optimal development from the perspectives of four different types of stakeholders: a government planner, a land developer, a hydrologist, and a conservationist subject to certain development constraints. Four different objective functions are posed that are consistent with each of these stakeholders’perspectives. We illustrate the differences in consequences on future development given these different objective functions in a stylized representation for Montgomery County, Maryland. Solutions to Smart Growth from the individual perspectives vary considerably. Tradeoff tables are presented that illustrate the consequences experienced by each stakeholder depending on the viewpoint that has been optimized. Although couched in the context of an illustrative example, this study emphasizes the need to apply rigorous, quantitative tools in a meaningful framework to address Smart Growth. The result is a tool that a range of parties can use to plan future development in ways that are environmentally and fiscally responsible and economically viable.  相似文献   
164.
Many species show fission-fusion group dynamics because it has clear advantages for flexibly exploiting heterogeneous environments. However, the mechanisms by which these dynamics arise are not well known. We used a hierarchical Bayesian model to disentangle the different influences on spider monkey (Ateles geoffroyi) individual fissions and fusions, including the three dimensions of fission-fusion dynamics (subgroup size, dispersion, and composition). Furthermore, we considered the influences of other individuals also leaving or joining a subgroup at the same time. We found that the most important influence on individual fissions and fusions is whether other individuals are also doing the same. Subgroup size and dispersion did not have clear effects on the probability that an individual fissioned or fusioned, while individuals tended to leave subgroups that were biased toward the opposite sex and to join subgroups that were biased toward their own sex. The networks constructed by the inter-individual influences during fissions and fusions were cohesive and did not show assortativity by sex or by degree. Individuals had a similar degree in both networks and each was influenced by a different set of individuals, suggesting a high fluidity in the social networks. We suggest that these networks reflect the way in which information about the environment flows as individuals follow one another during fissions and fusions.  相似文献   
165.
166.
Several studies on individual physiological traits assume that past records may predict future performance. Marine mollusks, as other animals, show a wide range of between- and within-individual variation of physiological traits. However, in this group, almost nothing is known about the relative influence of genetic factors on that variation. Repeatability (R) is a measure of the consistency of the variation of a trait, which includes its genetic variance and represents the maximum potential value of its heritability (h 2). Traits that show high inter-individual variation and high repeatability levels could potentially evolve through selection (natural or artificial). We estimated the repeatability [using intra-class (τ) and Pearson-moment (r) correlation coefficients] of several physiological traits related to energy acquisition and allocation in juvenile Pacific abalone Haliotis discus hannai, maintained under controlled environment growing systems. In order to estimate the range of the R values and the effect of the time elapsed between measurements on these estimates, we measured these traits monthly during 6 months for each individual. Among the physiological traits, those related to energy allocation like oxygen consumption (standard metabolic rate, SMR) and ammonium excretion rates, and oxygen/nitrogen ratio (O/N), showed intermediate levels of repeatability (0.48, 0.55 and 0.39, respectively), when this was estimated by τ coefficient. However, the r estimation showed that SMR and O/N repeatability were significant and high (0.6–0.7 and 0.5–0.7, respectively) during the first 5 consecutive measurements, decreasing strongly (0.3 and 0.2, respectively) during the last measurement. For ammonia excretion, although repeatability (r) decreased from 0.8 to 0.5 during the 6 consecutive measurements, they remain significant during the experimental period. Therefore, our results indicate that for H. discus hannai juveniles, physiological traits like SMR, ammonia excretion and O/N are significantly repeatable (i.e. good predictors of future measurements) during a period of 4–5 months. These significant repeatability values suggest an important genetic control upon the phenotypic variation of these physiological traits, and could potentially respond to natural or artificial selection, and be used in genetic improvement programs. By contrast, those traits related to energy acquisition (i.e. ingestion, absorption and assimilation) and physiological efficiencies (i.e. net growth and scope for growth) showed very low levels of repeatability (0–0.07). This indicates that the phenotypic variation of these traits would be more influenced by environment rather than by genetic factors.  相似文献   
167.
The burning of kerosene in jet turbines is investigated for two reference flights with a Boeing 747-400 and an Airbus A320-200, representing the typical Lufthansa planes for long and middle distance. The ecological evaluation is performed by Life Cycle Assessment (LCA). Formation of condensation trails, which is a specific environmental impact caused by air traffic, has to be considered in addition to established LCA impact categories. Based on the ecological assessment, an improvement assessment is performed. Environmental performance of diesel fuel during the combustion in car engines is analysed based on available publications. The relevant parameters for the environmental impact of the combustion of diesel (aromatics content, reduction of sulphur content, the reduction of the density and raising of the cetane number) are discussed with regard to improvements of the exhaust qualities of kerosene. A reduction of the aromatics content promises to improve the emission of soot which should be further investigated.  相似文献   
168.
The first target of the Convention for Biological Diversity (Aichi target 1) was to increase public awareness of the values of biodiversity and actions needed to conserve it—a key prerequisite for other conservation targets. Monitoring success in achieving this target at a global scale has been difficult; however, increased digitization of human life in recent decades has made it easier to measure people's interests at an unprecedented scale and allows for a more comprehensive evaluation of Aichi target 1 than previously attempted. We used Google search volume data for over a thousand search terms related to different aspects of biodiversity and conservation to evaluate global interest in biodiversity and its conservation. We also investigated the correlation of interest in biodiversity and conservation across countries to variables related to biodiversity, economy, demography, research, education, internet use, and presence of environmental organizations. From 2013 to 2020, global searches for biodiversity components increased, driven mostly by searches for charismatic fauna (59% of searches were for mammal species). Searches for conservation actions, driven mostly by searches for national parks, decreased since 2019, likely due to the COVID-19 pandemic. Economic inequality was negatively correlated with interest in biodiversity and conservation, whereas purchasing power was indirectly positively correlated with higher levels of education and research. Our results suggest partial success toward achieving Aichi target 1 in that interest in biodiversity increased widely, but not for conservation. We suggest that increased outreach and education efforts aimed at neglected aspects of biodiversity and conservation are still needed. Popular topics in biodiversity and conservation could be leveraged to increase awareness of other topics with attention to local socioeconomic contexts.  相似文献   
169.
人力资本法评估农业污染地下水环境价值损失   总被引:1,自引:0,他引:1  
应用人力资本法(HCA)评估了华北典型高产粮区地下水资源硝酸盐污染的价值损失.引用国外的研究结果,建立了硝酸盐污染浓度与健康损害的剂量反应关系,分病因预测了地下水污染超标区增加的死亡人口数量.按照潜在寿命损失人年(YPLL)的计算方法,构造了人力资本损失总量估算函数.应用该函数评估了研究区农业面源污染地下水资源的价值损失为860.8万元/a,相当于每公顷耕地面积上增加外部环境成本293.9元/a.  相似文献   
170.
The increasing use of computers since the 1960s, has implied the digitization of observations in meteorology, oceanography and other observational sciences. Enough data has been accumulated to suggest that some patterns of evolution in the world may be discernable. The present article deals with what appears as changing tides around Canada.  相似文献   
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