Phytoplankton and zooplankton were monitored during 2 years in four eutrophic shallow lakes (two turbid and two clear water) from two wetland reserves in Belgium. In each wetland, phytoplankton biomass was significantly higher in the turbid lake than in the clear water lake. Although total macrozooplankton biomass and the contribution of daphnids to total zooplankton biomass was comparable in the clear water and the turbid lakes, the grazing pressure of macrozooplankton on phytoplankton as estimated from zooplankton to phytoplankton biomass ratios was higher in the clear water lakes. Estimated grazing by daphnids in the clear water lakes was always high in spring. In summer, however, daphnid biomass was low or daphnids were even absent during prolonged periods. During those periods phytoplankton was probably controlled by smaller macrozooplankton or by submerged macrophytes through nutrient competition, allelopathic effects or increased sedimentation rates in the macrophyte vegetation. 相似文献
We report silicon isotopic determinations for USGS rock reference materials BHVO-1 and BHVO-2 using a Nu Plasma multi-collector (MC)-ICP-MS, upgraded with a new adjustable entrance slit, to obtain medium resolution, as well as a stronger primary pump and newly designed sampler and skimmer cones ("B" cones). These settings, combined with the use of collector slits, allowed a resolution to be reached that was sufficient to overcome the 14N16O and 14N2 interferences overlying the 30Si and the 28Si peaks, respectively, in an earlier set-up. This enabled accurate measurement of both δ30Si and δ29Si. The δ value is expressed in per mil variation relative to the NBS 28 quartz reference material. Based on data acquired from numerous sessions spread over a period of six months, we propose a recommended average δ30Si of −0.33 ± 0.05‰ and −0.29 ± 0.11‰ (2se) for BHVO-1 and BHVO-2, respectively. Our BHVO grand mean silicon isotope composition (δ30Si =−0.31 ± 0.06‰) is significantly more negative than the only published value for BHVO-2, but is in very good agreement with the recently established average value of ocean island basalts (OIB), confirming the conclusion that the OIB reservoir has a distinct isotopic composition from the solar reservoir as sampled by chondrites. 相似文献
The lack of broad public support prevents the implementation of effective climate policies. This article aims to examine why citizens support or reject climate policies. For this purpose, we provide a cross-disciplinary overview of empirical and experimental research on public attitudes and preferences that has emerged in the last few years. The various factors influencing policy support are divided into three general categories: (1) social-psychological factors and climate change perception, such as the positive influences of left-wing political orientation, egalitarian worldviews, environmental and self-transcendent values, climate change knowledge, risk perception, or emotions like interest and hope; (2) the perception of climate policy and its design, which includes, among others, the preference of pull over push measures, the positive role of perceived policy effectiveness, the level of policy costs, as well as the positive effect of perceived policy fairness and the recycling of potential policy revenues; (3) contextual factors, such as the positive influence of social trust, norms and participation, wider economic, political and geographical aspects, or the different effects of specific media events and communications. Finally, we discuss the findings and provide suggestions for future research.
Policy relevance
Public opinion is a significant determinant of policy change in democratic countries. Policy makers may be reluctant to implement climate policies if they expect public opposition. This article seeks to provide a better understanding of the various factors influencing public responses to climate policy proposals. Most of the studied factors include perceptions about climate change, policy and its attributes, all of which are amenable to intervention. The acquired insights can thus assist in improving policy design and communication with the overarching objective to garner more public support for effective climate policy. 相似文献
The feasibility of green growth is studied in the context of climate change. As carbon emissions are easier to quantify than many other types of environmental pressure, it will be possible to reach a more definite conclusion about the likelihood of green growth than has been possible in the long-standing historical debate on growth versus the environment. We calculate the rate of decoupling between gross domestic product (GDP) and GHG emissions needed to achieve internationally agreed climate targets. Next, eight arguments are considered that together suggest that fast decoupling will be very difficult. Subsequently, we examine the main lines of research used by proponents of green growth to support their viewpoint, including theoretical arguments, exercises with integrated assessment models, and studies of the environmental Kuznets curve hypothesis. It will be concluded that decoupling as a main or single strategy to combine economic and environmental aims should be judged as taking a very large risk with our common future. To minimize this risk we need to seriously consider reducing our dependence on growth. This requires a fundamental change of focus in both economic research and policy.
Policy relevance
Currently, green growth is the only strategy of mainstream economists and policy makers to address climate change. This article demonstrates that such an exclusive focus is very risky due to the scale of the challenge and the existence of various barriers to the fast decoupling of GHG emissions from economic output. It seems that the only option to combine environmental and economic objectives is reducing the dependence of our economies on growth. Finding strategies in line with this requires a fundamental change of focus in both economic research and policy. 相似文献
Srinivasan et al. provide an interesting overview of the challenges for long-term socio-hydrological predictions. Although agreeing with most of the statements made, we argue for the need to take socio-hydrological analysis a step further and add some fundamental considerations, especially concerning the crucial importance of many (conscious and unconscious) assumptions made upfront of the modelling exercise. Eventual assumptions of technological determinism need correction: Models are not “value-free”, but uncertain, subjective and a product of the society in which they were shaped. It is important to acknowledge this uncertainty and bias when making decisions based on socio-hydrological models, considering also that these models are “social and political actors” in and by themselves. Furthermore, socio-hydrological models require a transdisciplinary approach, since physical water availability is only one of the boundary conditions for society. Last but not least, interaction with stakeholders remains important to enable understanding of what the variable of interest is. 相似文献
For the development of sustainable, efficient risk management strategies for the hydrological extremes of droughts and floods, it is essential to understand the temporal changes of impacts, and their respective causes and interactions. In particular, little is known about changes in vulnerability and their influence on drought and flood impacts. We present a fictitious dialogue between two experts, one in droughts and the other in floods, showing that the main obstacles to scientific advancement in this area are both a lack of data and a lack of commonly accepted approaches. The drought and flood experts “discuss” available data and methods and we suggest a complementary approach. This approach consists of collecting a large number of single or multiple paired-event case studies from catchments around the world, undertaking detailed analyses of changes in impacts and drivers, and carrying out a comparative analysis. The advantages of this approach are that it allows detailed context- and location-specific assessments based on the paired-event analyses, and reveals general, transferable conclusions based on the comparative analysis of various case studies. Additionally, it is quite flexible in terms of data and can accommodate differences between floods and droughts. 相似文献
The Target infrastructure has been specially built as a storage and compute infrastructure for the information systems derived from Astro-WISE. This infrastructure will be used by several applications that collaborate in the area of information systems within the Target project. It currently consists of 10 PB of storage and thousands of computational cores. The infrastructure has been constructed based on the requirements of the applications. The storage is controlled by the Global Parallel File System of IBM. This file system takes care of the required flexibility by combining storage hardware with different characteristics into a single file system. It is also very scalable, which allows the system to be extended into the future, while replacing old hardware with new technology. 相似文献