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511.
Abstract: Traditionally, marine resources have been managed such that controls on new developments are implemented only when harmful effects on other environmental or economic interests can be demonstrated. This approach poses particular problems for the conservation of coastal cetaceans because potential threats to their populations are diverse and likely to interact, individual threats may result from multiple sources, and the problems inherent in studying cetaceans result in considerable scientific uncertainty and low statistical power to detect any effects. Consequently, many countries are adopting integrated coastal management programs and precautionary management principles. In practice, however, issues continue to be dealt with within traditional frameworks that require demonstration of harm. Because cetaceans are long-lived, they demand long-term studies, and populations could decline to dangerously low levels before management action is taken. We illustrate these problems using a case study from the Moray Firth, Scotland. This inshore area will soon be designated and managed as a "special area of conservation" to protect bottlenose dolphins (   Tursiops truncatus ) under the European Community's Habitats Directive. The population is small and isolated, and it faces a wide range of potential threats, but there remains considerable uncertainty over the magnitude of each threat. We combined power analysis and population viability analysis to explore the relative consequences of adopting either traditional or precautionary approaches to management. In this case, our results reaffirm the need for precautionary management. More generally, we illustrate how this approach can be used to provide a more scientific basis for determining the level of precaution required to address particular management issues in this and other marine systems.  相似文献   
512.
Triclosan (TCS) is a broad-spectrum bactericide, highly toxic to algae, which is released into the environment via wastewater effluents. Predicted no-effect concentrations (PNECs) for aquatic biota have been proposed in the literature, varying from 1.4 to 1,550 ng/L, reflecting contradicting protection goals. In this work, six rivers in the state of São Paulo were monitored for TCS and caffeine, a tracer for untreated sewage disposal, over a period of more than 1 year. From 71 samples analyzed, 32 contained TCS at concentrations above the limit of quantification, ranging from 2.2 to 66 ng/L, corresponding to a frequency of exceedance of the lowest PNEC of 86 % (six out of seven sites). No correlation between TCS and caffeine was observed, and one of the reasons for that could be the different use patterns in the local populations. Given the high values found in the investigated rivers, TCS seems to be a strong candidate in the priority list of compounds that should be regulated in Brazil to preserve the aquatic environment.  相似文献   
513.
Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was <10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75?±?0.52 μg L–1) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was <7 % for total As and <3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.  相似文献   
514.
Ammonia (NH3) emission from livestock manures used in agriculture reduces N uptake by crops and negatively impacts air quality. This laboratory study was conducted to evaluate NH3emission from different livestock manures applied to two soils: Candler fins sand (CFS; light-textured soil, pH 6.8 and field capacity soil water content of 70 g kg? 1) from Lake Alfred, Florida and Ogeechee loamy sand (OLS; medium-textured soil, pH 5.2 and field capacity soil water content of 140 g kg? 1) from Savannah, Georgia. Poultry litter (PL) collected from a poultry farm near Douglas, Georgia, and fresh solid separate of swine manure (SM) collected from a farm near Clinton, North Carolina were used. Each of the soil was weighed in 100 g sub samples and amended with either PL or SM at rates equivalent to either 0, 2.24, 5.60, 11.20, or 22.40 Mg ha? 1 in 1L Mason jars and incubated in the laboratory at field capacity soil water content for 19 days to monitor NH3 volatilization. Results indicated a greater NH3 loss from soils amended with SM compared to that with PL. The cumulative NH3volatilization loss over 19 days ranged from 4 to 27% and 14 to 32% of total N applied as PL and SM, respectively. Volatilization of NH3 was greater from light-textured CFS than that from medium-textured OLS. Volatilization loss increased with increasing rates of manure application. Ammonia volatilization was lower at night time than that during the day time. Differences in major factors such as soil water content, temperature, soil type and live stock manure type influenced the diurnal variation in volatilization loss of NH3 from soils. A significant portion (> 50%) of cumulative NH3 emission over 19 d occurred during the first 5–7 d following the application of livestock manures. Results of this study demonstrate that application of low rates of livestock manure (≤ 5.60 Mg ha? 1) is recommended to minimize NH3 emissions.  相似文献   
515.
Air pollution has plagued the urban areas of our Nation for many years, both as a serious health hazard and as a costly economic burden. Users of the air as a waste disposal medium have treated it as a free resource with no regard for the damages incurred by receptors of the dirty air. Unfortunately, no self-regulating market forces exist that will bring this diseconomy into an acceptable equilibrium. An outside regulating force, which can affect abatement of air pollution, is needed to achieve control of air pollution to a level acceptable to a community. A prerequisite of any proposed regulatory action to be applied by an outside force, however, is the need to define an acceptable level of pollution. One means of accomplishing the task is to apply an economic evaluation, in the form of a cost-benefit analysis, to the problem. Previous analyses of the economic aspects of air pollution have stressed only one side of the problem. That is, they have dealt only with the cost of control or the damages caused by air pollution. No analysis has combined both aspects into a meaningful analysis of the overall economic impact. The objective of this paper is to present a technique that can be used to find the level of pollution abatement in an area that balances the cost of controlling pollution with the benefits received from its control. To present a clearer picture of this technique and its results, it has been applied to the Washington, D. C. area to find the optimum level of particulate abatement. This method is generally applicable to any area, in which an air pollution problem exists.  相似文献   
516.
Estimates of 1973–1982 annual SO2 emissions from electric utility plants are presented in this paper. Results are based on analyses of plant level data collected by the U.S. Department of Energy on consumption and quality of fuels burned. Emissions are estimated from known information about fuel consumption, sulfur content, ash content, and control equipment. Results show that electric utility emissions decreased 16% from 1973 to 1982 and that these reductions were due to the use of lower sulfur coals and to the operation of flue gas desulfurization equipment.  相似文献   
517.
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519.
Ecological restoration is an increasingly important tool for managing and improving highly degraded or altered environments. Faced with a large number of sites or ecosystems to restore, and a diverse array of restoration approaches, investments in ecological restoration must be prioritized. Nevertheless, there are relatively few examples of the systematic prioritization of restoration actions. The development of a general theory for ecological restoration that is sufficiently sophisticated and robust to account for the inherent complexity of restoration planning, and yet is flexible and adaptable to ensure applicability to a diverse array of restoration problems is needed. In this paper we draw on principles from systematic conservation planning to explicitly formulate the ‘restoration prioritization problem’. We develop a generalized theory for static and dynamic restoration planning problems, and illustrate how the basic problem formulation can be expanded to allow for many factors characteristic of restoration problems, including spatial dependencies, the possibility of restoration failure, and the choice of multiple restoration techniques. We illustrate the applicability of our generic problem definition by applying it to a case study - restoration prioritization on The Irvine Ranch Natural Landmark in Southern California. Through this case study we illustrate how the definition of the general restoration problem can be extended to account for the specific constraints and considerations of an on-the-ground restoration problem.  相似文献   
520.
Recovery and conservation of threatened species require adequate institutional responses. We tested an approach to systematically identify and measure how an institutional framework acknowledges threats and required responses for the recovery of endangered species. We measured institutional functional fit with a drivers-pressure-state-impacts-response (DPSIR) model integrated with a quantitative text mining method and qualitative analysis of statutory instruments to examine regulatory responses that support the recovery of 2 endangered species native to Australia, the bridled nailtail wallaby (Onychogalea fraenata) and the Eastern Bristlebird (Dasyornis brachypterus). The key components of the DPSIR model were present in the institutional framework at statutory and operational levels, but some institutional gaps remained in the protection and recovery of the Eastern Bristlebird, including feral predator control, weed control, and grazing management in some locations. However, regulatory frameworks varied in their geographic scope and the application and implementation of many instruments remained optional. Quantitative text mining can be used to quickly navigate a large volume of regulatory documents, but challenges remain in selection of terms, queries of co-occurrence, and interpretation of word frequency counts. To inform policy, we recommend that quantitative assessments of institutional fit be complemented with qualitative analysis and interpreted in light of the sociopolitical and institutional context.  相似文献   
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