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1.
This paper analyzes a unique dataset collected during a 2006 national survey of U.S. households to explore the effectiveness of common household recycling policies for metals, glass, and plastics: curbside recycling, drop-off recycling, deposit–refund systems (bottle bills), and marginal pricing for household waste. After estimating either generalized ordered logit or multinomial logit models, we find that the most important determinants of household recycling are people's attitudes toward recycling. Our results also suggest that omitting internal variables (perceived recycling obstacles and benefits as well as moral considerations) may bias policy coefficients. Socio-economic variables are typically not statistically significant, with the exceptions of young adults and of African Americans who tend to recycle less than others. Policies with the largest odds ratios are curbside recycling (which is further strengthened if recycling is mandatory), followed by the presence of drop-off collection centers nearby. Bottle bills are also statistically significant but their odds ratios are smaller, possibly because refunds are relatively small and typically do not change for years. Finally, marginal pricing appears to have a limited impact on recycling. These results suggest avenues for improving household recycling at a time when recycling rates appear to be plateauing.  相似文献   

2.
Loss of fish habitat in North America has occurred at an unprecedented rate through the last century. In response, the Canadian Parliament enacted the habitat provisions of the Fisheries Act. Under these provisions, a “harmful alteration, disruption, or destruction to fish habitat” (HADD) cannot occur unless authorised by Fisheries and Oceans Canada (DFO), with legally binding compensatory habitat to offset the HADD. The guiding principle to DFO’s conservation goal is “no net loss of the productive capacity of fish habitats” (NNL). However, performance in achieving NNL has never been evaluated on a national scale. We investigated 52 habitat compensation projects across Canada to determine compliance with physical, biological, and chemical requirements of Section 35(2) Fisheries Act authorisations. Biological requirements had the lowest compliance (58%) and chemical requirements the highest (100%). Compliance with biological requirements differed among habitat categories and was poorest (19% compliance) in riparian habitats. Approximately 86% of authorisations had larger HADD and/or smaller compensation areas than authorised. The largest noncompliance in terms of habitat area occurred in riverine habitat in which HADDs were, on average, 343% larger than initially authorised. In total, 67% of compensation projects resulted in net losses of habitat area, 2% resulted in no net loss, and 31% achieved a net gain in habitat area. Interestingly, probable violations of the Fisheries Act were prevalent at half of the projects. Analyses indicated that the frequency of probable Fisheries Act violations differed among provinces. Habitat compensation to achieve NNL, as currently implemented in Canada, is at best only slowing the rate of habitat loss. In all likelihood, increasing the amount of authorised compensatory habitat in the absence of institutional changes will not reverse this trend. Improvements in monitoring and enforcement are necessary to move towards achieving Canada’s conservation goals.  相似文献   

3.
In spring 2011, an unprecedented flood hit the complex eastern United States (U.S.)–Canada transboundary Lake Champlain–Richelieu River (LCRR) Basin, destructing properties and inducing negative impacts on agriculture and fish habitats. The damages, covered by the Governments of Canada and the U.S., were estimated to C$90M. This natural disaster motivated the study of mitigation measures to prevent such disasters from reoccurring. When evaluating flood risks, long‐term evolving climate change should be taken into account to adopt mitigation measures that will remain relevant in the future. To assess the impacts of climate change on flood risks of the LCRR basin, three bias‐corrected multi‐resolution ensembles of climate projections for two greenhouse gas concentration scenarios were used to force a state‐of‐the‐art, high‐resolution, distributed hydrological model. The analysis of the hydrological simulations indicates that the 20‐year return period flood (corresponding to a medium flood) should decrease between 8% and 35% for the end of the 21st Century (2070–2099) time horizon and for the high‐emission scenario representative concentration pathway (RCP) 8.5. The reduction in flood risks is explained by a decrease in snow accumulation and an increase in evapotranspiration expected with the future warming of the region. Nevertheless, due to the large climate inter‐annual variability, short‐term flood probabilities should remain similar to those experienced in the recent past.  相似文献   

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Ecological restoration is increasingly becoming a primary component of broader environmental and water resources management programs throughout the world. The New Zealand Department of Conservation implemented Project River Recovery (PRR) in 1991 to restore unique braided gravel-bed river and wetland habitat in the Upper Waitaki Basin in New Zealand’s high country of the South Island, which has been severely impacted by hydroelectric power development. These braided rivers are highly dynamic, diverse, and globally important ecosystems and provide critical habitat to numerous native wading and shore bird species, including several threatened species such as the black stilt. The objective of this study was to review and summarize PRR after more than 10 years of implementation to provide information and transfer knowledge to other nations and restoration programs. Site visits were conducted, discussions were held with key project staff, and project reports and related literature were reviewed. Primary components of the program include pest plant and animal control, wetland construction and enhancement, a significant research and monitoring component, and public awareness. The study found that PRR is an excellent example of an ecological restoration program focusing on conserving and restoring unique habitat for threatened native bird species, but that also includes several secondary objectives. Transfer of knowledge from PRR could benefit ecological restoration programs in other parts of the world, particularly riverine floodplain and braided river restoration. PRR could achieve even greater success with expanded goals, additional resources, and increased integration of science with management, especially broader consideration of hydrologic and geomorphologic effects and restoration opportunities.  相似文献   

6.
Hodgkin–Huxley model, describing generation of action potentials in axons’ membranes, has been used for appreciation of the possible mechanisms of electromagnetic fields influence on neurons’ electrical activity. It follows from the carried calculations that flowing through an axon of the external current pulses, which have an area of rise, an area of DC, and an area of drop, does not influence own excitation pulses passage if periods of rise and drop are slope enough. Depending on the external current parameters, own excitation pulses may not be influenced or may be suppressed at greater velocity of rise and drop of an external current. Moreover, induced excitation pulses appear at definite parameters of an external current. In the case, when at passage through an axon of an external current, own excitation pulses follow one by one (paired pulse facilitation), and the second pulse may be suppressed if its level will not be increased additionally in comparison with the case of an external current absence. It is possible that such increase happens “automatically” as a result of “tuning” (adaptation) of axons to the conditions of flowing through them of an external current. It may be an explanation of the phenomena observed in experiments.  相似文献   

7.
The present study investigated the influence of electromagnetic fields (EMF), similar to that emitted by mobile phones, on brain activity. Ten women and ten men, matched for age and educational level, performed a short memory task (Wechsler test), with simultaneous Electroencephalogram (EEG) recordings at 15 scalp electrodes, both without (baseline) and with exposure to an 1,800 MHz signal. The EEG energy was found concentrated at the four basic EEG bands [α (8–13 Hz), β (14–30 Hz), δ (0–4 Hz), and θ (5–7 Hz)]. The analysis revealed that in the presence of EMF, the energy of the β band was significantly greater for females than for males at the majority of the electrodes. Since beta oscillation is associated with the shift of attention during the perception, these findings may indicate that the particular EMF (1,800 MHz signal) exerts an influence on this brain activity, which appears to be gender-related.  相似文献   

8.
Estuarine areas worldwide are under intense pressure due to human activities such as upstream dam building. Shorebirds strongly depend on estuarine intertidal flats during migration and wintering periods and so are particularly vulnerable to such impacts, whose magnitude will depend on the availability of alternative feeding habitats. In this study we analyze if man-made saltpans can represent an alternative habitat for wintering and migrating shorebirds in the Guadiana estuary, a wetland that is already experiencing environmental changes due to the building of the Alqueva reservoir, the largest in Western Europe. We compared the use of mudflats and saltpans as feeding areas by several shorebird species before the construction of the dam. A dataset with 26 years of counts data was also analyzed in order to detect any long-term trend in shorebirds abundance. We concluded that saltpans, in particular the fully mechanized, can be used as an alternative habitat by larger species during winter and southward migration, thus playing a major role in minimizing the possible effects of sediment loss due to dam building. In contrast, smaller species were particularly dependent on mudflats to feed. A significant change in population trends, from positive to negative, was detected for two species. Although we still have no evidence that this is directly linked to dam building, this result and documented changes that limit primary productivity justifies the implementation of a long-term monitoring scheme of shorebird populations in this estuary. We also reinforce the need to manage the saltpans as key habitats for shorebirds.  相似文献   

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In order to prevent ‘an impending neem failure’, from the incidence of the twin problems of the neem scale insect infestations and neem dieback, six authenticated provenances (Allahabad, Karnataka, Jodphur, Madinipur, Mukkambu and Annur), from the natural range of the species in India, were collected and appraised for survival in a degraded land in Kano, Nigeria. Established in a completely randomised block design with four replications, the trial was conducted with a view to restrengthening and/or replacing the already weakened Local Land Race of the species in the study area. There was a statistically significant difference in the survival of the seven provenances. The established differences are between Allahabad 83% (6.40 SEM), Mukkambu 83% (6.40 SEM), Annur 76% (4.90 SEM), Jodphur 63% (15.09 SEM) and Madinipur 56% (6.73 SEM), on the one hand, and Karnataka 17% (1.91SEM) and the Local Land Race, with 13% (0.13 SEM), on the other hand. The research recommends Allahabad and Mukkambu 83% (6.40 SEM) based on this outstanding performance.  相似文献   

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/ An index of upland wildlife habitat was developed to investigate patterns and changes in habitat over time, using four years (1920, 1940, 1964, 1987) and the state of Illinois as an example. The index was composed of two subdivisions that described, at the county level, the quantity of wildlife habitat and a third subdivision that described farming disturbances that impacted the quality of the habitat. Data came from the US Census of Agriculture. The first subdivision that reflected quantity of habitat was called the wildlife habitat subdivision and was the sum of percentage woodland on farms, percentage farmland in nonrow crops, and percentage farmland in set-aside programs. The second subdivision that reflected the quantity of habitat was termed the soil-related features subdivision and was the sum of the percentage of farmland that was not highly erodible, the percentage of farmland in soil-protecting crops, and the percentage of farmland in conservation tillage. The third subdivision, reflecting the quality of the habitat, was the farming disturbance subdivision and was the sum of the percentage of grazing and the percentage of land on which fertilizers, pesticides, and herbicides were applied. Overall, major decreases occurred between 1920 and 1987 in the subdivisions reflecting the quantity of wildlife habitat and a major increase occurred in the subdivision associated with farming disturbance, reflecting the intensification of agriculture in the state. However, there was variability throughout the state, with some counties being more favorable to wildlife (as measured by the subdivisions) than others. Most of the changes within the state for the subdivisions reflecting quantity of upland wildlife habitat occurred during 1940 while changes in the farming disturbance subdivision (reflecting habitat quality) occurred in 1964. By 1987, the western and southern parts of Illinois were the most favorable for wildlife as reflected in all three subdivisions. Upland wildlife harvest indices were related to the subdivisions in 1964 and 1987, when harvest indices were available. Cottontail and northern bobwhite harvests were higher in counties with higher amounts of the wildlife habitat subdivision in both years. Cottontail harvest was also higher in counties with lower levels of the farming disturbance subdivision in 1964 and higher levels of soil-related features subdivision in 1987. Indices at the county level have the potential to be used in a multiscale analysis to investigate the impact of policy changes on large-scale areas of the Midwest and to develop regional perspectives of the impacts of agriculture on upland wildlife and their habitats.KEY WORDS: Upland wildlife; Habitat; Agriculture; Illinois  相似文献   

13.
Arthropods constitute well over one-half of the species of higher life on the planet and are the dominant terrestrial life form on the planet. Unfortunately, very little is known about most arthropod species. There are an estimated 163,487 species of insects in North America, of which only 66% are taxonomically known. Similarly, there are an estimated 35,514 species of North American arachnids, of which only 9316 are described; over 73% have yet to be discovered and described. Without the basic taxonomic and life history knowledge for most of the terrestrial species (i.e., arthropods) of North American ecosystems, land managers are faced with the challenge of developing, selecting, and managing biotic reserves and habitat conservation plans for which they know very little about the majority of organisms found within such reserves or covered by such plans. With respect to arthropods, this challenge includes taking into account poorly described species being used as political tools to stop development (as opposed to actually protecting a truly endangered species), thus confounding the habitat conservation planning process and ensuring that "surprises" in the form of new listings will occur within any multispecies habitat plan. Finally, using various scenarios and assumptions, estimates of the true number of endangered insects and arachnids are provided to illustrate the fact that the suspected number of threatened, endangered, and extinct species is probably low by at least an order of magnitude.  相似文献   

14.
Experimentally induced acute inflammation in rats is a good model system which includes the complexity and dynamics of the processes; moreover there are many defined markers for following and estimating changes in an observed system. In this paper, we discuss an in vivo model of acute inflammation induced by carrageenan. Carrageenan-induced paw edema is a model of non-infectious acute inflammatory reaction to assess the contribution of mediators involved in vascular changes associated with acute inflammation and potential treatments. A complex approach into the investigation of possible effects of static magnetic fields (SMF) action on experimentally induced acute inflammation in rats (by measurements of the levels of specific stress markers) is very important in understanding the possible inflammatory mitigation effects, pain relief, and oxidative stress state of an organism. This approach could help for better understanding of the possible mechanisms of interaction of dynamic processes such as inflammation healing and pain relief with external SMF (25 mT at 10, 20 and 30 min exposure time). Results indicate that SMF with B = 25 mT for 30 min diminished the inflammatory process and decreased the levels of inflammatory markers (fibrinogen) and stress markers (ACTH, Cor) into the blood plasma in rats as when compared with sham exposed animals. The exact mechanism by which SMF contributes to the acceleration of inflammatory healing and decrease of inflammation markers in blood plasma in rats still remains unclear. We assume that two possible mechanisms exist. One is the direct interaction of SMF with free active oxygen forms (free radicals) affected by their membrane processes and related with the physiological functions. Another possible mechanism might be related to dynamic regulation of inflammation healing process.  相似文献   

15.
Exploitation of certain resources within a protected area on a sustainable basis could contribute to higher living standards of rural people, particularly those in poor countries, and decrease conflicts between these populations and park authorities. This article presents data from a case study of Kopaonik National Park (NP), Serbia, which is a park with natural resources, most notably bilberries, which have always been relied on by local people. Vaccinium myrtillus traditionally has been collected for decades in Kopaonik NP and used by local people. However, little is known about the socioeconomic and ecological relations that affect the collection and use of this species. The aim of the present study was to understand how local people collect bilberries in Kopaonik NP and what their attitudes toward the park are. Household questionnaire data were used to examine how local people collect bilberries and how to improve the relations between local people and NP authorities. The survey questionnaire included 52 households from 7 local communities, and we applied a purposive sampling strategy. In addition, expert interviews were conducted, and from these data we obtained a broader understanding of the relation between local people and NP authorities. The results indicate that in Kopaonik NP, there is a conflict between pickers and NP authorities. Sustainable management should be directed toward the protection of bilberries. Education of local people is a key element in the sustainable collection and protection of natural resources.  相似文献   

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17.
The theoretical concept, “asset specificity,” is applied to real data in the context of Danish nature conservation network planning in order to produce illustrative examples of an economic measure of the network’s vulnerability to exogenous shocks to the species composition. Three different measures of asset specificity are quantified from the shadow value of eliminating a key species from the individual grid cells. This represents a novel approach and a different interpretation of the term, as it is conventionally used as a qualitative indicator in the transaction cost economics literature. Apart from supplementing existing cost measures with an indicator of risk associated with investments in protected areas, this study demonstrates how the estimation and interpretation of various asset specificity measures for geographical areas may qualify policy makers’ choice of policy instrument in conservation planning. This differs from the more intuitive approach of basing policy instrument choice solely on the rarity of the species in a given area.  相似文献   

18.
Many species of conservation concern are spatially structured and require dispersal to be persistent. For such species, altering the distribution of suitable habitats on the landscape can affect population dynamics in ways that are difficult to predict from simple models. We argue that for such species, individual-based and spatially explicit population models (SEPMs) should be used to determine appropriate levels of off-site restoration to compensate for on-site loss of ecologic resources. Such approaches are necessary when interactions between biologic processes occur at different spatial scales (i.e., local [recruitment] and landscape [migration]). The sites of restoration and habitat loss may be linked to each other, but, more importantly, they may be linked to other resources in the landscape by regional biologic processes, primarily migration. The common management approach for determining appropriate levels of off-site restoration is to derive mitigation ratios based on best professional judgment or pre-existing data. Mitigation ratios assume that the ecologic benefits at the site of restoration are independent of the ecologic costs at the site of habitat loss. Using an SEPM for endangered red-cockaded woodpeckers, we show that the spatial configuration of habitat restoration can simultaneously influence both the rate of recruitment within breeding groups and the rate of migration among groups, implying that simple mitigation ratios may be inadequate.  相似文献   

19.
The radiological impact of radionuclides released to the terrestrial environment is usually predicted with mathematical models in which the transfer of radionuclides from soil to the plant is described with the transfer factor (TF). This paper questions the validity of the protocols proposed by the International Atomic Energy Agency to measure TF in the field and in greenhouses conditions. We grew maize (Zea mays L.) both in the field after a surface application of radionuclides ((54)Mn, (57)Co, (65)Zn, and (134)Cs) and in a greenhouse with the same soil that has received the same fertilization and that had been previously sieved and homogeneously labeled with the same radionuclides before being repacked in pots. The analysis of the displacement of radionuclides in the field soil profile showed a higher concentration of the surface-applied radionuclides in the preferential flow path (PFP) in comparison to the soil matrix indicating that they infiltrated heterogeneously in the soil profile due to the structure-induced non-uniform water flow. A significantly higher recovery of (57)Co and (134)Cs was observed in the plants grown in the field soil, whereas no differences in the recovery of (54)Mn and (65)Zn between the two experiments were detected. These results suggest that (i) under field conditions the soil-to-plant transfer of radionuclides that co-exist as stable elements present at low concentrations in the soil and in the plant is higher than that measured under greenhouse conditions and (ii) the implicit assumption made when calculating the TF (that radionuclides are homogeneously distributed in the soil profile) is not valid, thereby preventing the calculation of an average concentration to obtain the TF parameter.  相似文献   

20.
This study examines the spatial and statistical relationships between social vulnerability (SV) and neighbourhood walkability across three large U.S. cities with different urban typologies and development patterns: Charlotte, NC (a low-density, fast-growing “Sunbelt” city); Pittsburgh, PA (a moderate density, shrinking “Rust Belt” city); and Portland, OR (a progressive West Coast city known for its sprawl-containment policies). Binary logistic regression, independent-samples t-tests, and mapping techniques are employed to determine whether neighbourhoods with high SV (i.e. older populations, higher poverty rates, more service occupations, lower educational attainment, and a higher proportion of minorities) are as likely as those with low SV to exhibit a high degree of walkability. The publically available Walk Score® metric, based on proximity to amenities, street network connectivity, and density, was used as a proxy for neighbourhood walkability. The results indicate significant variability among cities, with Charlotte exhibiting the greatest potential for inequitable access to walkable urban environments and the most prominent concentration of “walk-vulnerable” block groups (BGs) with high SV and low walkability. Both Portland and Pittsburgh exhibited more equitable access when comparing BGs with high and low SV; however, they each presented unique spatial patterns, visualised using a series of maps.  相似文献   

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