城市污水处理厂好氧颗粒污泥的特性

对城市污水处理厂曝气池中筛选出的好氧颗粒污泥进行了分析.结果表明,这些颗粒污泥的直径主要在0.2～0.8 mm范围;平均圆度为1.29;沉淀速率约在10～42 m h-1之间;比耗氧速率(SOUR)为14.2～18.9 mg g-1h-1,小于活性污泥;挥发性物质占总固体的量与活性污泥基本相似.这些颗粒污泥占污泥总量的0.1%～0.5%.颗粒污泥的激光共聚焦扫描显微镜(CLSM)图像显示:颗粒污泥内部几乎都由胞外聚合物(EPS)组成;细菌主要分布在颗粒污泥表面至100μm厚度区域,少部分分布在100～400μm厚度区域.     

Modeling the Effects of Anthropogenic Habitat Change on Savanna Snake Invasions into African Rainforest

Abstract:  We used a species-distribution modeling approach, ground-based climate data sets, and newly available remote-sensing data on vegetation from the MODIS and Quick Scatterometer sensors to investigate the combined effects of human-caused habitat alterations and climate on potential invasions of rainforest by 3 savanna snake species in Cameroon, Central Africa: the night adder (Causus maculatus) , olympic lined snake (Dromophis lineatus) , and African house snake (Lamprophis fuliginosus) . Models with contemporary climate variables and localities from native savanna habitats showed that the current climate in undisturbed rainforest was unsuitable for any of the snake species due to high precipitation. Limited availability of thermally suitable nest sites and mismatches between important life-history events and prey availability are a likely explanation for the predicted exclusion from undisturbed rainforest. Models with only MODIS-derived vegetation variables and savanna localities predicted invasion in disturbed areas within the rainforest zone, which suggests that human removal of forest cover creates suitable microhabitats that facilitate invasions into rainforest. Models with a combination of contemporary climate, MODIS- and Quick Scatterometer-derived vegetation variables, and forest and savanna localities predicted extensive invasion into rainforest caused by rainforest loss. In contrast, a projection of the present-day species-climate envelope on future climate suggested a reduction in invasion potential within the rainforest zone as a consequence of predicted increases in precipitation. These results emphasize that the combined responses of deforestation and climate change will likely be complex in tropical rainforest systems.     

Assessing Risk to Birds from Industrial Wind Energy Development via Paired Resource Selection Models

When wildlife habitat overlaps with industrial development animals may be harmed. Because wildlife and people select resources to maximize biological fitness and economic return, respectively, we estimated risk, the probability of eagles encountering and being affected by turbines, by overlaying models of resource selection for each entity. This conceptual framework can be applied across multiple spatial scales to understand and mitigate impacts of industry on wildlife. We estimated risk to Golden Eagles (Aquila chrysaetos) from wind energy development in 3 topographically distinct regions of the central Appalachian Mountains of Pennsylvania (United States) based on models of resource selection of wind facilities (n = 43) and of northbound migrating eagles (n = 30). Risk to eagles from wind energy was greatest in the Ridge and Valley region; all 24 eagles that passed through that region used the highest risk landscapes at least once during low altitude flight. In contrast, only half of the birds that entered the Allegheny Plateau region used highest risk landscapes and none did in the Allegheny Mountains. Likewise, in the Allegheny Mountains, the majority of wind turbines (56%) were situated in poor eagle habitat; thus, risk to eagles is lower there than in the Ridge and Valley, where only 1% of turbines are in poor eagle habitat. Risk within individual facilities was extremely variable; on average, facilities had 11% (SD 23; range = 0–100%) of turbines in highest risk landscapes and 26% (SD 30; range = 0–85%) of turbines in the lowest risk landscapes. Our results provide a mechanism for relocating high‐risk turbines, and they show the feasibility of this novel and highly adaptable framework for managing risk of harm to wildlife from industrial development. Evaluación del Riesgo para las Aves por el Desarrollo de Energía Eólica Industrial Mediante Modelos de Selección de Recursos Pareados.     

Permanent Sovereignty over Natural Resources Recent Developments in the Mineral Sector

The United Nations has been concerned with the application of the principle of permanent sovereignty over natural resources and the exercise by developing countries of control over the exploitation of their natural resources for many years. Probably the most serious concern in recent years has been the impact of the world-wide recession on investment in mineral exploration and production facilities in developing countries. Growing difficulties in attracting investment funds have caused a re-examination of existing investment, mining and tax legislation. Recent mineral development agreements assign a higher priority to investment promotion; this reflects a change from earlier years—during the 1960s and 1970s—when many developing countries were in a stronger position because equity and loan capital for mineral projects was more readily available. Pendant de nombreuses années, les Nations Unies se sont préoccupées de la mise en oeuvre par les pays en développement du principe de leur souveraineté permanente sur leurs ressources naturelles ainsi que de l'exercice de leur droit de contrôle sur la mise en production de ces mêmes ressources. En toute vraisemblance, le problème le plus sérieux qui s'est posé au cours de ces dernières années a été le poids de la récession économique mondiale sur les investissements dans les domaines de l'exploration et de la production minières dans les pays en développement. Les difficultés grandissantes à obtenir des capitaux ont conduit à réexaminer les investissements existants ainsi que la législation minière et fiscale. De récents accords de développement minier réservent une priorité plus importante à la promotion des investissements. Ceci reflète un changement par rapport aux années précédentes—celles des décennies 60 et 70—au cours desquelles de nombreux pays en développement avaient une position beaucoup plus forte car il était plus facile de trouver des capitaux propres et des prêts financiers pour les projets miniers. Las Naciones Unidas ha estado interesado en la aplicación del principio de soveranía permanente de los recursos naturales y el ejercicio del control por parte de los países en desarrollo sobre su explotación. Probablemente la mayor preocupación en an?os recientes ha sido el impacto de la recesión mundial de las inversiones en la exploración y producción de minerales en los países en desarrollo. La dificultad creciente en atraer inversiones ha motivado el examen de la legislación existente sobre inversiones, minería e impuestos. Recientes acuerdos sobre desarrollo de minerales asigna mayor prioridad a la promoción de inversiones; esto representa un cambio con respecto a an?os anteriores—décadas del 60 y 70—cuando los países en desarrollo tenían una posición fuerte debido a que el capital de riesgo y préstamos para proyectos en minería eran abundante.     

The Northwest Forest Plan: Origins, Components, Implementation Experience, and Suggestions for Change

Abstract:  In the 1990s the federal forests in the Pacific Northwest underwent the largest shift in management focus since their creation, from providing a sustained yield of timber to conserving biodiversity, with an emphasis on endangered species. Triggered by a legal challenge to the federal protection strategy for the Northern Spotted Owl ( Strix occidentalis caurina ), this shift was facilitated by a sequence of science assessments that culminated in the development of the Northwest Forest Plan. The plan, adopted in 1994, called for an extensive system of late-successional and riparian reserves along with some timber harvest on the intervening lands under a set of controls and safeguards. It has proven more successful in stopping actions harmful to conservation of old-growth forests and aquatic systems than in achieving restoration goals and economic and social goals. We make three suggestions that will allow the plan to achieve its goals: (1) recognize that the Northwest Forest Plan has evolved into an integrative conservation strategy, (2) conserve old-growth trees and forests wherever they occur, and (3) manage federal forests as dynamic ecosystems.     

Avoiding Pitfalls of Using Species Distribution Models in Conservation Planning

Abstract:   Museum records have great potential to provide valuable insights into the vulnerability, historic distribution, and conservation of species, especially when coupled with species-distribution models used to predict species' ranges. Yet, the increasing dependence on species-distribution models in identifying conservation priorities calls for a more critical evaluation of model robustness. We used 11 bird species of conservation concern in Brazil's highly fragmented Atlantic Forest and data on environmental conditions in the region to predict species distributions. These predictions were repeated for five different model types for each of the 11 bird species. We then combined these species distributions for each model separately and applied a reserve-selection algorithm to identify priority sites. We compared the potential outcomes from the reserve selection among the models. Although similarity in identification of conservation reserve networks occurred among models, models differed markedly in geographic scope and flexibility of reserve networks. It is essential for planners to evaluate the conservation implications of false-positive and false-negative errors for their specific management scenario before beginning the modeling process. Reserve networks selected by models that minimized false-positive errors provided a better match with priority areas identified by specialists. Thus, we urge caution in the use of models that overestimate species' occurrences because they may misdirect conservation action. Our approach further demonstrates the great potential value of museum records to biodiversity studies and the utility of species-distribution models to conservation decision-making. Our results also demonstrate, however, that these models must be applied critically and cautiously.     

Paying the Extinction Debt in Southern Wisconsin Forest Understories

Abstract: The lack of long‐term baseline data restricts the ability to measure changes in biological diversity directly and to determine its cause. This hampers conservation efforts and limits testing of basic tenets of ecology and conservation biology. We used a historical baseline survey to track shifts in the abundance and distribution of 296 native understory species across 82 sites over 55 years in the fragmented forests of southern Wisconsin. We resurveyed stands first surveyed in the early 1950s to evaluate the influence of patch size and surrounding land cover on shifts in native plant richness and heterogeneity and to evaluate changes in the relative importance of local site conditions versus the surrounding landscape context as drivers of community composition and structure. Larger forests and those with more surrounding forest cover lost fewer species, were more likely to recruit new species, and had lower rates of homogenization than smaller forests in more fragmented landscapes. Nearby urbanization further reduced both alpha and beta understory diversity. Similarly, understory composition depended strongly on local site conditions in the original survey but only weakly reflected the surrounding landscape composition. By 2005, however, the relative importance of these factors had reversed such that the surrounding landscape structure is now a much better predictor of understory composition than are local site conditions. Collectively, these results strongly support the idea that larger intact habitat patches and landscapes better sustain native species diversity and demonstrate that humans play an increasingly important role in driving patterns of native species diversity and community composition.