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21.
Contamination problems are often characterized by complex mixtures of chemicals. There are two conceptual models usually used to evaluate patterns of mixture toxicity: Concentration Addition (CA) and Independent Action (IA). Deviations from these models as synergism, antagonism and dose dependency also occur. In the present study, single and mixture toxicity of atrazine, dimethoate, lindane, zinc and cadmium were tested in Porcellionides pruinosus and Enchytraeus albidus, using avoidance as test parameter. For both species patterns of antagonism were found when exposed to dimethoate and atrazine, synergism for lindane and dimethoate exposures (with the exception of lower doses in the isopod case study) and concentration addition for cadmium and zinc occurred, while the exposure to cadmium and dimethoate showed dissimilar patterns.This study highlights the importance of dose dependencies when testing chemical mixtures and that avoidance tests can also be used to asses the effects of mixture toxicity.  相似文献   
22.
The effectiveness of wheat straw charcoal (WSC) and mustard straw charcoal (MSC) as adsorbents for the removal of nitrate-nitrogen from water has been investigated. Commercial activated carbon (CAC) was used as a standard for comparison. The adsorption effectiveness of MSC was highest followed by CAC and WSC irrespective of the concentration of nitrate-nitrogen in the range of 0-25mg/l. The effects of temperature in the range of 15-28 degrees C on adsorption by WSC and MSC have also been investigated. It was observed that the temperature dependence of the adsorption effectiveness of MSC was higher than that of WSC and CAC. It is concluded that the MSC can be used for the in situ treatment by adsorption of nitrate-nitrogen in underground and surface water.  相似文献   
23.
This article reviews the influence of two specific European Union (EU) laws, the Birds and Habitats Directives, on the choice of national policy instruments by Member States. Both Directives leave the choice for policy instruments to manage the sites designated under the Directives to the Member States. Using path dependency as a leading concept, this article analyses the continuity or changes in policy instruments due to the implementation of the Directives in 15 countries. This article shows that the tendency to use existing instruments to implement EU policy is limited, as in almost all countries new instruments were developed. Yet, states do tend to choose instruments from their predominant policy instrument mix and preferred implementation style to address the management requirements of the Directives. Additionally, in Central and Eastern European countries where the implementation of EU policy coincided with a process of transition to a market economy, new instruments were introduced outside the existing implementation style. The introduction of new policy instruments is the result of historical turns, domestic pressure and a shift to new modes of governance. National case studies are needed to shed more light on the interaction between EU policy and domestic factors during the process of instrument choice.  相似文献   
24.
Summary. In a wind tunnel bioassay the effect of three concentrations of natural extracts of (1) Scots pine wood, Pinus sylvestris, and (2) larval frass on the behavioural response of unmated females and males of the old house borer, Hylotrupes bajulus, was tested and compared to the behavioural effects of the male-produced sex pheromone (3R)-3-hydroxy-2-hexanone. The influence on the behaviour of both sexes was found to be equally significant for the two higher concentrated hexane extracts of wood and larval frass. Therefore several synthetic monoterpenes present in the extracts and ethanol were tested at the two higher concentrations (1:100, 1:1000 vol/vol). Among the higher concentrated monoterpenoid hydrocarbons [(+)-α-pinene, (+)-β-pinene, (+)-limonene], only α-pinene increased the activity, orientation towards scent source and interest towards conspecifics. The tests with higher concentrated ethanol and the oxygenated monoterpenes [(-)-verbenone, (-)-trans-pinocarveol, (+)-terpinen-4-ol, (+)-α-terpineol, (-)-myrtenol] revealed that verbenone is the most effective stimulant for the females, followed by trans-pinocarveol, terpinen-4-ol and α-terpineol. For males, terpinen-4-ol was the only mediator significantly inducing attraction and orientation towards the scent source combined with an interest in conspecifics apparent by fighting or courtship behaviour. Males did not respond to verbenone which is a main compound of larval frass. Myrtenol and ethanol were ineffective in both sexes. In fact behavioural observations suggest that the beetles were repelled by the high dose of myrtenol. Using the ten-fold lower dose of the synthetic monoterpenes (1:1000 vol/vol), all semiochemicals except myrtenol lost activity. Myrtenol, however, induced behavioural responses, like increased activity and orientation towards scent source, only at the low concentration. Based on the results, primary attraction of unmated old house borer is probably mediated by monoterpenes of coniferous wood, while secondary attraction to infested wood would occur in response to volatiles of larval frass. Received 5 May 1999; accepted 30 September 1999  相似文献   
25.
An overarching challenge of natural resource management and biodiversity conservation is that relationships between people and nature are difficult to integrate into tools that can effectively guide decision making. Social–ecological vulnerability offers a valuable framework for identifying and understanding important social–ecological linkages, and the implications of dependencies and other feedback loops in the system. Unfortunately, its implementation at local scales has hitherto been limited due at least in part to the lack of operational tools for spatial representation of social–ecological vulnerability. We developed a method to map social–ecological vulnerability based on information on human–nature dependencies and ecosystem services at local scales. We applied our method to the small‐scale fishery of Moorea, French Polynesia, by combining spatially explicit indicators of exposure, sensitivity, and adaptive capacity of both the resource (i.e., vulnerability of reef fish assemblages to fishing) and resource users (i.e., vulnerability of fishing households to the loss of fishing opportunity). Our results revealed that both social and ecological vulnerabilities varied considerably through space and highlighted areas where sources of vulnerability were high for both social and ecological subsystems (i.e., social–ecological vulnerability hotspots) and thus of high priority for management intervention. Our approach can be used to inform decisions about where biodiversity conservation strategies are likely to be more effective and how social impacts from policy decisions can be minimized. It provides a new perspective on human–nature linkages that can help guide sustainability management at local scales; delivers insights distinct from those provided by emphasis on a single vulnerability component (e.g., exposure); and demonstrates the feasibility and value of operationalizing the social–ecological vulnerability framework for policy, planning, and participatory management decisions.  相似文献   
26.
The study was conducted to investigate people’s forest dependency and contributions of forests to the livelihoods in the three hill districts of Chittagong Hill Tracts (CHT), Bangladesh. The study revealed that forest resources contribute significantly to rural community’s livelihoods and economic well-being. Using generalized logistic regressions, this study has also investigated the socioeconomic factors that affect people’s dependency on forest resources of CHT. The study revealed that people’s income from forest and forest-related occupation was positively aligned with their forest dependency. However, their education level significantly reduced their dependency on forest resources. Thus, educating the forest-dependent people and supporting alternative income generation activities should be appreciated for effective forest management in CHT. This study will be helpful to forest and environmental policy makers for CHT.  相似文献   
27.
We propose asymmetric angular-linear multivariate regression models, which were motivated by the need to predict some environmental characteristics based on some circular and linear predictors. A measure of fit is provided through the residual analysis. Some applications using data from solar energy radiation experiment and wind energy are given. Received: September 2003 / Revised: February 2005  相似文献   
28.
不同磷效率基因型小麦对VAM真菌依赖性的影响因子及机理   总被引:5,自引:0,他引:5  
以高、中、低效3 个磷效率基因型小麦为试材,在w(P2O5) =20 mgkg 和60 mgkg 的水平下,接种或不接种两个VA菌根真菌Glomus mosseae 和Glomusversiforme,研究了影响小麦菌根依赖性的因子及机理.结果表明,在低磷水平下,小麦菌根依赖性的大小顺序为中效> 低效> 高效;对G. versiform 的依赖性大于对G. mosseae 的依赖性;而在高磷水平下,接种菌根表现出不同程度的生长抑制作用.相关分析发现,菌根依赖性与根冠比、根长、根毛长度、根毛密度、磷利用效率之间的相关性不显著;在低磷水平下,菌根依赖性与磷效率、根吸收效率之间呈极显著的负相关,与韧皮部蔗糖运输速率之间呈显著或极显著的正相关.认为影响不同磷效率基因型小麦菌根依赖性的主要因子是根的吸收效率;菌根依赖性、磷效率和韧皮部蔗糖运输速率均受根吸收效率影响  相似文献   
29.
The article explores the historical process of creating unjust environmental conditions in one geographical area in the Finnish capital, Helsinki. The study traces back the decision-making processes about placing environmentally burdensome, communal facilities, such as power plants, waste disposal and other infrastructural facilities. Also the lack of environmental amenities is investigated. The study covers a time period from the latter half of the nineteenth century to the 1980s. The historical analysis of the development of land-use decisions in the city is based on documentary and archival sources about the decision-making processes and it is conducted in the framework of distributive and procedural environmental justice. Four different periods of siting policies are identified. The motives for land-use decisions at each phase reflect geographical, political and historical reasoning. The concept of path dependency is introduced to explain, how environmental injustices were reproduced because of past paths of siting policies locked in subsequent decisions and created a negative twist of accumulating environmental burden.  相似文献   
30.
We discuss how the EU’s Renewable Energy Directive was designed to be mobile, and how it was moved to and implemented in Finland by translating it to enhance wood-based energy production through specific subsidies. We study policy-making as a mobile process, which approach has its original roots in political science and more recent basis in political geography. The article aims to develop conceptual understanding of how the mobility of a supranational policy is generated and how a policy is translated into complex and contentious geographical contexts. We aim to show that mobility of a directive is enabled by an empty governance space which is aimed to be ‘filled in’ in each spatial context, and that the filling in process makes each translation a contentious and path-dependent process. In Finland, the selected policy tools and practices continued the path-dependent ways of favouring forestry industry’s traditional position as the primary utiliser of forest resources.  相似文献   
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