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1.
Amending poultry litter with Al sulfate (alum) has proven effective in reducing water-soluble P in the litter and in runoff from fields that have received litter applications. Although its effectiveness has been demonstrated on a macroscopic scale in the field or in the poultry houses, little is known about P speciation in either alum-amended or unamended litter. This knowledge is important for the evaluation of long-term stability and bioavailability of P, which is a necessary prerequisite for the assessment of the sustainability of intensive poultry operations. Here we report results from an investigation of alum-amended poultry litter (PL) that combined a chemical extraction sequence with solid-state 31P nuclear magnetic resonance (NMR) spectroscopic analysis of the residues. Aluminum is predominantly found in the fine size separate (<125 microm), indicating that the alum added to the poultry houses hydrolyzed without being completely dispersed in the litter. The NMR spectra confirmed the hypothesis that calcium phosphate phases are only dissolved during extraction with dilute acid and phosphate associated with Al is mainly dissolved during extraction with NaOH. Extraction of phosphate associated with Al was incomplete, however, as evidenced by 31P NMR spectroscopy. It could also be demonstrated that the extraction sequence overestimates the calcium phosphate fraction by an order of magnitude in this particular sample. Results from sequential chemical extraction should therefore be used with caution when assessing the magnitude of different phosphate pools in poultry litter.  相似文献   

2.
Phosphate treatment of lead (Pb)-contaminated soils relies on the premise that Pb converts to the thermodynamically stable, insoluble mineral class of pyromorphites. Recent research showed that treatment performance is kinetically controlled and strongly dependent on soil pH; this study employed an acidic phosphate (P) form, monobasic calcium phosphate (MCP), to investigate treatment performance of Pb occurring in an alkaline-buffered and an acidic firing range soil. The results of leaching, X-ray powder diffraction (XRPD), and modeling analyses showed that P and Pb dissolution in the alkaline soil and transformation reactions were kinetically controlled, so that: (i) TCLP (toxicity characteristic leaching procedure) and SPLP (synthetic precipitation leaching procedure) results were poor to marginal even at high MCP dosages; (ii) brushite (Ca(HPO(4)).2H(2)O) and cerussite (PbCO(3)) persisted in XRPD patterns; and, (iii) geochemical modeling failed to predict leaching and phase assemblages. In the acidic soil, Pb-P reactions promoted further soil acidification, improved TCLP performance, and generated better agreement with the equilibrium-based model; however, SPLP and modeling results showed that Pb concentrations could not be reduced below 15 microg/L mainly due to the low soil pH. The marginal or inadequate Pb immobilization was observed in both soils despite the elevated MCP dosages, which were well in excess of the pyromorphite stoichiometric ratio (P/Pb = 0.6). Additionally, P leaching concentrations and rates were extremely high (>300 mg/L), under both SPLP and deionized (DI) water extraction conditions, and as predicted by thermodynamic equilibrium. The performance and sustainability of phosphate-based treatment therefore seem questionable.  相似文献   

3.
This paper explores whether ambitions to open up the traditional Swedish model of top-down conservation methods to local influences are indicative of an actual transition in governance of Swedish national park policy (NPP), and examines whether such a shift entails an increase in local influence over local interests and needs. Methodologically, we analyse a combination of governance types and incorporate theoretical definitions of power and accountability. The establishment of new governance arrangements – where power is shared, interactions promoted and accountability is directed downwards – indicates that Sweden's NPP is undergoing a change in its mode of governance. This change also seems to include ceding some influence to local interests, and the possibility of combining conservation with the utilisation of certain natural resources. The results of our research also provide valuable insights into when the establishment of shared-governance arrangements are likely to succeed; in short, this seems more likely when there are established sectors sited in a robust legal framework and where strong international commitments potentially play a role. In conclusion, we contend that when seeking diversified governance arrangements it is not enough simply to take local practices and customs into consideration – they have to be strengthened.  相似文献   

4.
Management effectiveness evaluation has been recognized as an important mechanism for both reporting on and improving protected area management. The Convention on Biological Diversity’s program of work on protected areas calls on all countries to implement such systems. In 2004, the first whole of system assessment of park management effectiveness, based on the IUCN-WCPA Management Effectiveness Evaluation Framework, was undertaken in New South Wales, Australia as part of a State of the Parks reporting requirement. This article describes the development of the State of the Parks assessment tool, its elements, and how it addresses the management effectiveness difficulties associated with assessments conducted across an extensive and diverse range of park types. The importance of engaging staff, at all levels, throughout the process is highlighted, as well as the adjustments made to the assessment tool based on staff feedback. While some results are presented, the main purpose of the article is to identify and discuss important procedural and methodological considerations. These include balancing quantitative and qualitative assessment approaches, achieving a comprehensive understanding of the management processes, and responding to any problems associated with assessments.  相似文献   

5.
With urban populations worldwide expected to witness substantial growth over the next decades, pressure on urban land and resources is projected to increase in response. For policy-makers to adequately meet the challenges brought about by changes in the dynamics of urban areas, it is important to clearly identify and communicate their causes. Floods in Douala (the most densely populated city in the central African sub-region), are being associated chiefly with changing rainfall patterns, resulting from climate change in major policy circles. We investigate this contention using statistical analysis of daily rainfall time-series data covering the period 1951–2008, and tools of geographic information systems. Using attributes such as rainfall anomalies, trends in the rainfall time series, daily rainfall maxima and rainfall intensity–duration–frequency, we find no explanation for the attribution of an increase in the occurrences and severity of floods to changing rainfall patterns. The culprit seems to be the massive increase in the population of Douala, in association with poor planning and investment in the city's infrastructure. These demographic changes and poor planning have occurred within a physical geography setting that is conducive for the inducement of floods. Failed urban planning in Cameroon since independence set the city up for a flood-prone land colonization. This today translates to a situation in which large portions of the city's surface area and the populations they harbor are vulnerable to the city's habitual annual floods. While climate change stands to render the city even more vulnerable to floods, there is no evidence that current floods can be attributed to the changes in patterns of rainfall being reported in policy and news domains.  相似文献   

6.
Simulations of stream temperatures showed a wide range of future thermal regimes under a warming climate — from 2.9°C warmer to 7.6°C cooler than current conditions — depending primarily on shade from riparian vegetation. We used the stream temperature model, Heat Source, to analyze a 37‐km study segment of the upper Middle Fork John Day River, located in northeast Oregon, USA. We developed alternative future scenarios based on downscaled projections from climate change models and the composition and structure of native riparian forests. We examined 36 scenarios combining future changes in air temperature (ΔTair = 0°C, +2°C, and +4°C), stream discharge (ΔQ = ?30%, 0%, and +30%), and riparian vegetation (post‐wildfire with 7% shade, current vegetation with 19% shade, a young‐open forest with 34% shade, and a mature riparian forest with 79% effective shade). Shade from riparian vegetation had the largest influence on stream temperatures, changing the seven‐day average daily maximum temperature (7DADM) from +1°C to ?7°C. In comparison, the 7DADM increased by 1.4°C with a 4°C increase in air temperature and by 0.7°C with a 30% change in discharge. Many streams throughout the interior western United States have been altered in ways that have substantially reduced shade. The effect of restoring shade could result in future stream temperatures that are colder than today, even under a warmer climate with substantially lower late‐summer streamflow.  相似文献   

7.
A national approach to the conservation of biodiversity in Australia's freshwater ecosystems is a high priority. This requires a consistent and comprehensive system for the classification, inventory, and assessment of wetland ecosystems. This paper, using the State of Victoria as a case study, compares two classification systems that are commonly utilized to delineate and map wetlands--one based on hydrology (Victorian Wetland Database [VWD]) and one based on indigenous vegetation types and other natural features (Ecological Vegetation Classes [EVC]). We evaluated the extent of EVC mapping of wetlands relative to the VWD classification system using a number of datasets within a geographical information system. There were significant differences in the coverage of extant EVCs across bioregions, different-sized wetlands, and VWD wetland types. Resultant depletion levels were markedly different when examined using the two systems, with depletion levels, and therefore perceived conservation status, of EVCs being significantly higher. Although there is little doubt that many wetland ecosystems in Victoria are in fact threatened, the extent of this threat cannot accurately be determined by relying on the EVC mapping as it currently stands. The study highlighted the significant impact wetland classification methods have in determining the conservation status of freshwater ecosystems.  相似文献   

8.
Synergistic combinations of climatic and land use changes have the potential to produce the most dramatic impacts on land cover. Although this is widely accepted, empirical examples, particularly involving deforestation in Latin America, are still very few. The geographic extent and causes of deforestation in subtropical seasonally dry forests of the world have received very little attention. This is especially true for the Chaco forests in South America, which are being lost at an alarming rate, sometimes higher than those reported for tropical forests. On this basis, the aims of this study were to analyze the changes in land cover that have occurred during the last three decades of the 20th century in the Chaco forests of central Argentina, and to explain the factors that have driven those changes. Results show major land cover changes. Approximately 80% of the area that was originally undisturbed forest is now occupied by crops, pastures, and secondary scrub. The main proximate cause of deforestation has been agricultural expansion, soybean cultivation in particular. This appears as the result of the synergistic convergence of climatic, technological, and socioeconomic factors, supporting the hypothesis of a multiple-factor explanation for forest loss, while providing one of the very few existing analyses of changes in subtropical forests of the world.  相似文献   

9.
“A skyscraper is as natural as a bird’s nest” –Alan Watts For millennia, people have altered freshwater ecosystems directly through water development and indirectly by global change and surrounding land-use activities. In these altered ecosystems, human impacts can be subtle and are sometimes overlooked by the people who manage them. This article provides two case studies near Boulder, Colorado that demonstrate how perceptions regarding these ecosystems affect their management. These examples are typical of lakes and streams along the Front Range of Colorado that are simultaneously natural and social in origin. Although natural, many of the region’s freshwater ecosystems are affected by ongoing ecologic, hydrologic, chemical, and geomorphic modifications produced by human activity. People and nature are both active participants in the production of these freshwater ecosystems. The concept of “hybridity,” borrowed from geographers and social scientists, is useful for describing landscapes of natural and social origin. Hybrid freshwater ecosystems are features of the humanized landscape and are derived from deliberate cultural activities, nonhuman physical and biological processes, and incidental anthropogenic disturbance. Our perceptions of “natural” freshwater ecosystems and what definitions we use to describe them influences our view of hybrid systems and, in turn, affects management decisions regarding them. This work stresses the importance of understanding the underlying societal forces and cultural values responsible for the creation of hybrid freshwater ecosystems as a central step in their conservation and management.  相似文献   

10.
The Tens Rule, as well as the last stage described therein, i.e., the proportion of established species that becomes pests, is frequently perceived by the scientific community to indicate that introduced established species have little impact on communities. This belief is dangerous because it strengthens the perspective of the general public and decision makers that the risks of species introductions are largely overestimated. It is often difficult to detect the actual negative impact of an introduced established species. It might be less apparent or indirect; it might be delayed or masked by the “noise” caused by other anthropogenic disturbances. It is also likely that numerous ecological interactions are still not detected or properly understood. Therefore, the ten-percent rule might be more of an indicator of our lack of understanding of the impacts that established introduced species produce than the actual ratio of such species that produces negative impacts. In such a state of affairs, adopting the precautionary principle is crucial. The scientific community must be much more cautious and responsible regarding the message it delivers to the general public and management authorities.  相似文献   

11.
Our lack of understanding of relationships between stream biotic communities and surrounding landscape conditions makes it difficult to determine the spatial scale at which management practices are best assessed. We investigated these relationships in the Minnesota River Basin, which is divided into major watersheds and agroecoregions which are based on soil type, geologic parent material, landscape slope steepness, and climatic factors affecting crop productivity. We collected macroinvertebrate and stream habitat data from 68 tributaries among three major watersheds and two agroecoregions. We tested the effectiveness of the two landscape classification systems (i.e., watershed, agroecoregion) in explaining variance in habitat and macroinvertebrate metrics, and analyzed the relative influence on macroinvertebrates of local habitat versus regional characteristics. Macroinvertebrate community composition was most strongly influenced by local habitat; the variance in habitat conditions was best explained at the scale of intersection of major watershed and agroecoregion (i.e., stream habitat conditions were most homogeneous within the physical regions of intersection of these two landscape classification systems). Our results are consistent with findings of other authors that most variation in macroinvertebrate community data from large agricultural catchments is attributable to local physical conditions. Our results are the first to test the hypothesis and demonstrate that the scale of intersection best explains these variances. The results suggest that management practices adjusted for both watershed and ecoregion characteristics, with the goal of improving physical habitat characteristics of local streams, may lead to better basin-wide water quality conditions and stream biological integrity.  相似文献   

12.
In developed countries, ecological restoration is a widely accepted practice to restore the productivity of degraded coal mine spoils and prevent mine‐degraded sites from acting as sources of pollution. During the past decade, ecologists realized the global need for ecological restoration, and the benefit of restoration is now assessed on the basis of ecosystem services that the restored lands can provide. In this article, the knowledge gap between crude reclamation and ecological restoration is examined, the steps crucial to ecological restoration in tropical conditions are identified, and simple guidelines are given for easy understanding. Restoration issues, such as modification of the forestry restoration approach, reestablishment of biodiversity, removal and reuse of topsoil during progressive and final stages of ecological restoration, drainage, promotion of a plant‐succession‐based approach, use of a grass–legume mixture as an initial colonizer, stabilization of steep slopes, and soil blanketing, are discussed. Those attributes of a degraded ecosystem that are responsible for the success of any restoration project are critically examined, and the opportunities provided by ecological restoration are explored.  相似文献   

13.
The relationship between the pattern of pollutant releases and neighborhood characteristics has been in the center of environmental justice debates for the last decades. One part of the discourse revolves around the question if the siting decision of polluting firms or the sorting decision of households is the explanatory factor for the pattern of pollutant releases. The aim of this study is to contribute to the discussion by investigating the potential correlation between polluting facilities and socioeconomic characteristics of neighborhoods in Ontario, Canada, using data from the Canadian census and National Pollutant Release Inventory. The analysis shows that when the results are considered from the perspectives of the siting decision of firms and sorting decision of households’ hypotheses, the results weigh in favor of the sorting decision of households.  相似文献   

14.
In the process of implementing EU policy, Member States sometimes introduce new policy instruments in cases where this is not obligatory. To better understand this phenomenon, this paper reviews three cases in which new instruments emerged and develops a methodology to trace back the influence of EU Directives on instrument choice. The method is illustrated by a narrative of the emergence of new management planning instruments during the implementation of the EU Habitats Directive in three EU Member States: Finland, Hungary and the Netherlands. Three key features of a policy instrument are defined, namely, its authoritative force, action content and governance design. These are used to measure the contribution of the Habitats Directive compared to other potential explanatory causes for the emergence of the new policy instrument. In all three reviewed countries a nested causal relationship between the Habitats Directive and the introduction of the new policy instrument is identified. Based on the relative contribution of the Habitats Directive to the emergence of the new instrument a distinction is made whether the Directive acted as a cause, catalyst or if conjunction occurred.  相似文献   

15.
Natural hazard investigators recommend that local governments adopt mitigation plans to help reduce hazard losses. However, such plans are unlikely to be effective unless a wide range of public stakeholders is involved in their creation. Previous research shows that stakeholder participation levels in hazard mitigation planning tend to be low, though there may be particular choices that local government planners can make to foster participation. We examine the importance of planners’ choices and role orientations (i.e., beliefs regarding appropriate behavior in the workplace) for participation levels in site plan review, wherein local governments review site plans for proposed development projects to ensure compliance between project design and applicable plans and policies. Using a national sample of 65 development projects located in areas subject to natural hazards, and bivariate and multivariate analyses, we examine whether participation levels during site plan review depend upon planners’ choices and role orientations, and whether participation levels are correlated with the incorporation of hazard mitigation techniques into development projects. We find significant correlations between participation levels and planners’ choices, between participation levels and planner’s role orientations, and between participation levels and the incorporation of hazard mitigation techniques. We encourage local government planners to revisit their beliefs, choices, and behaviors regarding public participation in site plan review.  相似文献   

16.
Numerous governments around the world have adopted statutory mandates on plan content based on the assumption that they lead to greater consistency and higher quality of plans. While a number of studies have examined the relationship between mandates to develop plans and plan quality, there has been limited study of the influence of state mandates for plan content on plan quality in a regional natural resource management (NRM) planning context. This paper explores the relationship between the quality of regional NRM plans between statutory and non-statutory NRM regions in New South Wales and Queensland, Australia. An analysis of 22 regional NRM plans indicates that there is no evidence of a relationship between plan quality and the presence of statutory mandates for regional NRM plans in New South Wales and Queensland. However, the paper identifies and discusses several other factors with unexpected relationships with an impact on the quality of NRM plans in New South Wales and Queensland, Australia.  相似文献   

17.
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19.
Technical and socio-economic characteristics are known to determine different types of fishers and their livelihood strategies. Faced with declining fish and water resources, small-scale fisheries engage into transformations in livelihood and fishing practices. The paper is an attempt to understand these changes and their socio-economic patterns, in the case of Singkarak Lake in West Sumatra, Indonesia. Based upon the hypothesis that riparian communities have diverse, complex yet structured and dynamic livelihood systems, the paper’s main objective is to study, document and model the actual diversity in livelihood, practices and performance of inland small-scale fisheries along the Singkarak Lake, to picture how households are adapted to the situation, and propose an updated, workable model (typology) of those for policy. Principal component analysis and cluster analysis were used to develop a typology of fishing households. The results show that small-scale fishers can be classified into different types characterized by distinct livelihood strategies. Three household types are identified, namely “farming fishers” households (type I, 30 %), “fishing farmers” households (type II, 30 %), and “mainly fishers” households (type III, 40 %). There are significant differences among these groups in the number of boats owned, annual fishing income, agriculture income and farming experience. Type I consists of farming fishers, well equipped, with high fishing costs and income, yet with the lowest return on fishing assets. They are also landowners with farming income, showing the lowest return on land capital. Type II includes poor fishing farmers, landowners with higher farming income; they show the highest return on land asset. They have less fishing equipment, costs and income. Type III (mainly fishers) consists of poorer, younger fishers, with highest return on fishing assets and on fishing costs. They have little land, low farming income, and diversified livelihood sources. The nature of their livelihood strategies is discussed for each identified group. This helps to understand the complexity and diversity of small-scale fishers, particularly in the study area which is still poorly known. This paper concludes with policy implication and possible management initiatives for environmentally prudent policy aiming at improvement of fishers’ livelihood.  相似文献   

20.
With the intention of bridging the ‘digital divide’ many programmes have been launched to provide computers for educational institutions, ranging from refurbishing second hand computers to delivering low cost new computers. The fast and economical provision of large quantities of equipment is one of the many challenges faced by such programmes. If an increase is to be achieved in the sustainability of computer supplies for schools, not only must equipment be provided, but also suitable training and maintenance delivered. Furthermore, appropriate recycling has to be ensured, so that end-of-life equipment can be dealt with properly. This study has evaluated the suitability of three computer supply scenarios to schools in Colombia: (i) ‘Colombian refurbishment’, -refurbishment of computers donated in Colombia, (ii) ‘Overseas refurbishment’, -import of computers which were donated and refurbished abroad, and (iii) ‘XO Laptop’, -purchase of low cost computers manufactured in Korea. The methods applied were: Material Flow Assessment, -to assess the quantities-, Life Cycle Assessment, -to assess the environmental impacts, and the application of the Multiple Attribute Utility Theory, -to analyse, evaluate and compare different scenarios. The most sustainable solution proved to be the local refurbishment of second hand computers of Colombian origin to an appropriate technical standard. The environmental impacts of such practices need to be evaluated carefully, as second hand appliances have to be maintained, require spare parts and sometimes use more energy than newer equipment. Providing schools with second hand computers from overseas and through programmes such as ‘One Laptop Per Child’ has the disadvantage that the potential for social improvements – such as creation of jobs and local industry involvement – is very low.  相似文献   

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