The core element of the Costa Rican forestry policy is a financial instrument called the environmental service payment. This
instrument rewards forest owners for the environmental services (the mitigation of greenhouse gases, the protection of watersheds
and scenic beauty, and the development of biodiversity) their forests provide. In this article, the experiences with this
new instrument are analyzed by focusing on the way interests are represented and access is granted, the openness of information
exchange, whether social learning occurred, and whether decision-making authority is shared. The analysis is based on a survey
conducted in the Huetar Norte Region and on in-depth interviews with the major stakeholders. The Costa Rican case indicates
that financial instruments can be used to share responsibilities and that stakeholders can successfully cooperate on forest
issues. It also shows that such a participatory approach is only promising if certain cultural, economic, organizational,
and political conditions are met. 相似文献
The concentrations of PM10 mass, PM2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter.
Methods
Daily PM10 and PM2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 ??g. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters.
Results
The 18-month mean PM10 and PM2.5 mass concentrations ranged from 15.4 ??g/m3 in Helsinki to 56.7 ??g/m3 in Athens and from 9.0 ??g/m3 in Helsinki to 25.0 ??g/m3 in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm3 in Helsinki to 24,180 part/cm3 in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM10 with the exception of Athens where PM2.5 comprised 43% of PM10. Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p?0.05.
Conclusions
Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies. 相似文献
This article reflects on the Costa Rican experiences with ecotourism by assessing the positive and negative environmental,
economic and social impacts of ecotourism development at four tourist destinations—Manuel Antonio, Monteverde, Tortuguero
and ASCOMAFOR. These destinations represent different stages of tourism development. The assessment shows that the development
of ecotourism has a dilemma character. Compared to alternative land-use options, ecotourism remains a promising development
strategy. However, it should be embedded in a broader process of capacity building. 相似文献
Monitoring and laboratory data play integral roles alongside fate and exposure models in comprehensive risk assessments. The principle in the European Union Technical Guidance Documents for risk assessment is that measured data may take precedence over model results but only after they are judged to be of adequate reliability and to be representative of the particular environmental compartments to which they are applied. In practice, laboratory and field data are used to provide parameters for the models, while monitoring data are used to validate the models' predictions. Thus, comprehensive risk assessments require the integration of laboratory and monitoring data with the model predictions. However, this interplay is often overlooked. Discrepancies between the results of models and monitoring should be investigated in terms of the representativeness of both. Certainly, in the context of the EU risk assessment of existing chemicals, the specific requirements for monitoring data have not been adequately addressed. The resources required for environmental monitoring, both in terms of manpower and equipment, can be very significant. The design of monitoring programmes to optimise the use of resources and the use of models as a cost-effective alternative are increasing in importance. Generic considerations and criteria for the design of new monitoring programmes to generate representative quality data for the aquatic compartment are outlined and the criteria for the use of existing data are discussed. In particular, there is a need to improve the accessibility to data sets, to standardise the data sets, to promote communication and harmonisation of programmes and to incorporate the flexibility to change monitoring protocols to amend the chemicals under investigation in line with changing needs and priorities. 相似文献
In the history of disasters in Venice, there are implications for modern times in terms of complex systems management and emerging threats, in particular from examples of risk management and resilience achieved by the Venetian state during outbreaks of the plague. In fourteenth century Venice, risk assessment the way we practice it today would fail to provide meaningful recommendations to reduce the casualty rate of the plague epidemic because the cause and transmission of the disease was not understood. Instead, a set of systemic actions across the social, economic, and transportation networks of the city taken by officials and doctors eventually slowed and arguably stopped the spread of the disease. These latter actions are an early example of what is now considered resilience management. Resilience management improves a complex system’s ability to prepare, absorb, recover, and adapt to unexpected threats and does so by address the capabilities at a system, rather than component, level. Resilience management can be a guide to addressing current issues of population growth and rising sea level in modern day Venice and across the globe. This paper calls for integration of resilience assessment in comprehensive risk and resilience management framework. 相似文献
Incorporation rates of inorganic carbon and its distribution between the organic matter and the skeleton have been measured using 14C tracer techniques on two species of symbiont-bearing benthonic foraminifera in the Gulf of Elat: Amphistegina lobifera (a perforate species) and Amphisorus hemprichii (an imperforate species). Under constant experimental conditions, incorporation rates of the radiotracer become linear with time after several hours in A. hemprichii and after one day in A. lobifera. A. lobifera showed a lag time of 24 h for skeletal incorporation, whereas in A. hemprichii uptake into the skeleton started within 2 h. Pulse-chase incubations in radioactive seawater, followed by unlabelled incubations, demonstrate transfer of photosynthetically acquired 14C into the skeleton of A. lobifera. No such transfer was found in A. hemprichii. The total 14C uptake by A. lobifera increased during the first 24 h of cold chase incubation. This increase suggests the existence of an internal inorganic carbon pool that was lost (probably evaporated) during the analysis of pulse incubations. However, during the following chase incubations, the 14C in this pool was incorporated mainly into the skeleton and retained during analysis, causing the increase in the total uptake. No such increase was found in A. hemprichii. Additional 14C uptake experiments on other species of the genera Operculina, Heterostegina and Borelis suggest that the differences in pathways for incorporation of carbon between A. lobifera and A. hemprichii can be generalized to the perforate and imperforate foraminiferal groups. In perforate species, respired carbon originally taken up through photosynthesis is partly recycled into the skeleton. In imperforate species such a transfer has not been demonstrated. Perforate species seem to have a large internal inorganic carbon pool which serves mainly for calcification and possibly also for photosynthesis, while imperforate species may take up carbon for calcification directly from seawater or have a very small inorganic carbon pool. 相似文献
Summary Ecological and behavioral data from long-term field studies of known individuals in two closely related squirrel monkey species (Saimiri oerstedi and S. sciureus) were used to examine hypotheses about the source of variation in female bonding among group-living primates. Social relationships in species which live in cohesive groups are thought to depend on the nature of competition for resources. S. oerstedi and S. sciureus both live in large groups and are subject to intense predation. Direct feeding competition both between and within groups is extremely low in S. oerstedi; in this species female relationships are undifferentiated, no female dominance hierarchy is evident and females disperse from their natal group. S. sciureus also experiences very low levels of between-group competition, but within-group direct competition for resources is frequent; this species demonstrates differentiated female relationships, a female dominance hierarchy, and female philopatry. The correlated ecological and social variables found in these two congeners further minimize the minor effects of phylogenetic differences and emphasize the importance of food distribution in determining social characteristics.
Offprint requests to: S. Boinski 相似文献
The desorption kinetics of in situ chlorobenzenes (dichlorobenzenes, pentachlorobenzene and hexachlorobenzene) and 2,4,4′-trichlorobiphenyl (PCB-28) were measured with a gas-purge technique for river Rhine suspended matter sampled in Lobith, The Netherlands. This suspended matter is the main source of sediment accumulation in lake Ketelmeer. In lake Ketelmeer sediment earlier observations showed that slow and very slow fractions dominate the desorption profile.
For the river Rhine suspended matter, only for PCB-28 a fast desorbing fraction of around 1.6% could be detected. The observed rate constants were on the average 0.2 h−1 for fast desorption, 0.004 h−1 for slow desorption, and 0.00022 h−1 for very slow desorption. These values are in agreement with previous findings for the sediment from lake Ketelmeer and with available literature data on fast, slow, and very slow desorption kinetics.
The results from this study show the similarity of desorption profiles between river Rhine suspended matter, and the top layer sediment from lake Ketelmeer. This indicates that slow and very slow fractions are already present in material forming the top layer of lake Ketelmeer, and were not formed after deposition of this material in the lake. The absence of detectable fast fractions for most compounds could be caused by the absence of recent pollution of the suspended matter. But, the observations may also be explained by a rapid disappearance of compounds from the fast fraction due to a combination of a high affinity of very slow sites for these compounds, and their relatively high volatility. 相似文献