Influence of Processing Additives on the Degradation of Melt-Pressed Films of Poly(ε-Caprolactone) and Poly(Lactic Acid)

Melt-pressed films of polycaprolactone (PCL) and poly(lactic acid) (PLA) with processing additives, CaCO₃, SiO₂, and erucamide, were subjected to pure fungal cultures Aspergillus fumigatus and Penicillium simplicissimum and to composting. The PCL films showed a rapid weight loss with a minor reduction in the molecular weight after 45 days in A. fumigatus. The addition of SiO₂ to PCL increased the rate of (bio)erosion in A. fumigatus and in compost. The use of a slip additive, erucamide, was shown to modify the properties of the film surface without decreasing the rate of bio(erosion). Both the rate of weight loss and the rate of molecular weight reduction of PCL increased with decreasing film thickness. The addition of CaCO₃ to PLA significantly reduced the thermal degradation during processing, but it also reduced the rate of the subsequent (bio)degradation in the pure fungal cultures. PLA without additives and PLA containing SiO₂ exhibited the fastest (bio)degradation, followed by PLA with CaCO₃. The degradation of the PLA films was initially governed by chemical hydrolysis, followed by an acceleration of the weight change and of the molecular weight reduction. PLA film subjected to composting exhibits a rapid decrease in molecular weight, which then remains unchanged during the measurement period, probably because of crystallization.     

Solid waste treatment within the framework of life-cycle assessment

Traditionally, treatment of solid waste has been given limited attention in connection with life-cycle assessments (LCAs). Often, only the amounts of solid wastes have been noted. This is unsatisfactory since treatment of solid waste, e.g. by landfilling or incineration, is an operation, requiring inputs and producing outputs, which should be described in the inventory of an LCA, in parallel to other operations. However, there are difficulties in describing emissions from solid waste treatments and there is a need for development of such methods. In this paper an approach for describing emissions from incineration and landfilling is outlined. Methodological questions concerning the time-frame and allocation principles are discussed. Methods for estimating potential emissions from landfilling of municipal solid waste and industrial wastes are suggested. The methods are used for calculating potential emissions from landfilling of some typical wastes. These emissions are compared with the emissions from other stages in the life cycle for some materials and wastes. it is shown that the potential emissions from landfilling are, for some products, of importance for the final results. Hence, if emissions from landfilling are neglected, or underestimated, results and conclusions in an LCA may be misleading.     

自然保护区、恢复力和动态景观

在这个日益被人类活动所改变的世界里,保护生物多样性对于维持有恢复力的生态系统和确保生态系统产品的可持续流动以及对社会的服务是至关重要的.但是,现有的自然保护区和国家公园不大可能结合生态系统的长期和大尺度的动态.因此,保护策略必须包括大面积的人类利用经营的土地.为了能使生态系统在大规模的自然和人为干扰之后得以重组,以生态存储形式出现的空间恢复力是必备的前提.生态存储包括那些能使生态系统得以重组的物种、相互作用和结构,它的组成部分可能出现在干扰斑块中,也可能出现在周围的景观中.现有的静态自然保护区应该由动态自然保护区加以补充,例如生态休闲地和动态演替保护区,这些都是在景观尺度上模拟自然干扰状况,进行生态系统经营的组成部分.     

Stereotypical rapid source level regulation in the harbour porpoise biosonar

Some odontocetes and bats vary both click intensity and receiver sensitivity during echolocation, depending on target range. It is not known how this so-called automatic gain control is regulated by the animal. The source level of consecutive echolocation clicks from a harbour porpoise was measured with a hydrophone array while the animal detected an aluminium cylinder at 2, 4 or 8?m distance in a go/no-go paradigm. On-axis clicks had source levels of 145–174?dB re 1?μPa peak-to-peak. During target-present trials the click trains reached comparable source levels independent of the range to the target after three clicks. After an additional click, the source level was reduced for the 2 and 4?m trials until it equalled the one-way transmission loss. During target-absent trials, the source level remained high throughout the entire click train. Given typical values of harbour porpoise inter-click intervals, the source level reduction commenced within a few 100?ms from the first click in the click train. This may indicate a sub-cortically regulated source level regulation in the harbour porpoise.     

Are experienced people affected by a pre-set default option—Results from a field experiment

The objective of the present paper is to investigate the robustness of the well-known result that pre-set default options determine people's choices. We do so by conducting a field experiment among environmental economists attending a large international conference on environmental economics. The participants were, at the time of registration, randomly allocated to different treatments related to carbon offsetting. What differs from earlier default studies is that our subjects have good knowledge about the good at hand. We investigate whether the choices of these experienced individuals are affected by a pre-set default option, and we also study the effect of a treatment with no pre-set default option. Our results, together with previous findings, indicate that the effect of a default option attenuates with experience.     

Redundancy and response diversity of functional groups: implications for the resilience of coral reefs

To improve coral reef management, a deeper understanding of biodiversity across scales in the context of functional groups is required. The focus of this paper is on the role of diversity within functional groups in securing important ecosystem processes that contribute to the resilience of coral-dominated reef states. Two important components of species biodiversity that confer ecosystem resilience are analyzed: redundancy and the diversity of responses within functional groups to change. Three critical functional groups are used to illustrate the interaction between these two components and their role in coral reef resilience: zooxanthellae (symbiotic micro algae in reef-building corals), reef-building corals, and herbivores. The paper further examines the consequences of undermining functional redundancy and response diversity and addresses strategies to secure ecological processes that are critical for coral reef resilience.     

Basic principles and ecological consequences of changing water regimes: riparian plant communities

Recent research has emphasized the importance of riparian ecosystems as centers of biodiversity and links between terrestrial and aquatic systems. Riparian ecosystems also belong among the environments that are most disturbed by humans and are in need of restoration to maintain biodiversity and ecological integrity. To facilitate the completion of this task, researchers have an important function to communicate their knowledge to policy-makers and managers. This article presents some fundamental qualities of riparian systems, articulated as three basic principles. The basic principles proposed are: (1) The flow regime determines the successional evolution of riparian plant communities and ecological processes. (2) The riparian corridor serves as a pathway for redistribution of organic and inorganic material that influences plant communities along rivers. (3) The riparian system is a transition zone between land and water ecosystems and is disproportionately plant species-rich when compared to surrounding ecosystems. Translating these principles into management directives requires more information about how much water a river needs and when and how, i.e., flow variables described by magnitude, frequency, timing, duration, and rate of change. It also requires information about how various groups of organisms are affected by habitat fragmentation, especially in terms of their dispersal. Finally, it requires information about how effects of hydrologic alterations vary between different types of riparian systems and with the location within the watershed.     

Photo-identification, site fidelity, and movement of female gray seals (Halichoerus grypus) between haul-outs in the Baltic Sea

The growing gray seal population in the Baltic Sea has led to increased conflicts with fisheries. Despite limited data on gray seal ecology, management measures, such as culling, have been implemented recently. We studied movements and site fidelity of Baltic gray seals using mark-recapture analysis based on photographic identification of individuals (photo-id). Seals were photographed at the major summer haul-out sites. Profile photographs of the head and neck were matched using purpose-written software to generate a database of capture histories from 1995-2000. The haul-outs were grouped into seven areas. Darroch's method (20) for a two-sample capture-recapture census was adapted to estimate rates of movement between the areas. The majority of seals were estimated to remain within the same area, suggesting that Baltic gray seals exhibit a high degree of site fidelity during the summer, and that fidelity to a site lasts for more than one season.