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61.
In the context of international efforts to reduce the impactsof atmospheric NH3 and NH4 + (collectively, NHx), it is important to establish the link between NH3emissions and monitoring of NHx concentrations and deposition. This is equally relevant to situations where NH3emissions changes are certain (e.g. due to changed source sectoractivity), as to cases where NH3 abatement technologies havebeen implemented. Correct interpretation of adequate atmosphericmeasurements is essential, since monitoring data provide the onlymeans to evaluate trends in regional NH3 emissions.These issues have been reviewed using available measurements and modelling from nine countries. In addition to historic datasets,the analysis here considers countries where NH3 source sector activity changed (both increases and decreases) and countries where NH3 abatement policies have been implemented.In The Netherlands an `ammonia gap' was identified between the expected reduction and results of monitoring, and was attributedinitially to ineffectiveness of the abatement measures. The analysis here for a range of countries shows that atmospheric interactions complicate the expected changes, particularly sinceSO2 emissions have decreased at the same time, while at manysites the few years of available data show substantial inter-annual variation. It is concluded that networks need to beestablished that speciate between NH3 and aerosol NH4 +, in addition to providing wet deposition, and sample at sufficient sites for robust regional estimates to be established. Such measurements will be essential to monitor compliance of the international agreements on NH3 emission abatement.  相似文献   
62.
To reduce human casualties associated with explosive ordnance disposal, a wide range of protective wear has been designed to shield against the blast effects of improvised explosive devices and munitions. In this study, 4 commercially available bomb suits, representing a range of materials and armor masses, were evaluated against 0.227 and 0.567 kg of spherical C-4 explosives to determine the level of protection offered to the head, neck, and thorax. A Hybrid III dummy, an instrumented human surrogate [1], was tested with and without protection from the 4 commercially available bomb suits. 20 tests with the dummy torso mounted to simulate a kneeling position were performed to confirm repeatability and robustness of the dummies, as well as to evaluate the 4 suits. Correlations between injury risk assessments based on past human or animal injury model data and various parameters such as bomb suit mass, projected area, and dummy coverage area were drawn.  相似文献   
63.
A sample preparation method based on sintering, followed by analysis by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) for the simultaneous determination of chloride and bromide in diverse and mixed solid wastes, has been evaluated. Samples and reference materials of known composition were mixed with a sintering agent containing Na2CO3 and ZnO and placed in an oven at 560 °C for 1 h. After cooling, the residues were leached with water prior to a cation-exchange assisted clean-up. Alternatively, a simple microwave-assisted digestion using only nitric acid was applied for comparison. Thereafter the samples were prepared for quantitative analysis by ICP-SFMS. The sintering method was evaluated by analysis of certified reference materials (CRMs) and by comparison with US EPA Method 5050 and ion chromatography with good agreement. Median RSDs for the sintering method were determined to 10% for both chlorine and bromine, and median recovery to 96% and 97%, respectively. Limits of detection (LODs) were 200 mg/kg for chlorine and 20 mg/kg for bromine. It was concluded that the sintering method is suitable for chlorine and bromine determination in several matrices like sewage sludge, plastics, and edible waste, as well as for waste mixtures. The sintering method was also applied for determination of other elements present in anionic forms, such as sulfur, arsenic, selenium and iodine.  相似文献   
64.
Goals and performance targets are commonly used as tools in the policy-implementation process. In Sweden, environmental policy is operationalized through a system of environmental quality objectives that were adopted by the Swedish Riksdag in the late 1990s. The objectives describe what level of environmental quality Sweden should aim for within a generation, and are designed to guide decision making in all sectors of society. However, to guide decision making toward improved environmental quality, these objectives should satisfy a set of rationality (functionality) criteria; they should be precise, evaluable, approachable, motivating and coherent. In this paper, five Swedish environmental quality objectives are investigated through an application of the suggested criteria: (1) a balanced marine environment, flourishing coastal areas and archipelagos; (2) a magnificent mountain landscape; (3) a non-toxic environment; (4) natural acidification only; and (5) a good built environment. The aim of the paper is to bring the rationality of the objectives up for discussion, and to illustrate the range of issues and difficulties that are involved in choosing and assessing environmental policy goals.  相似文献   
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66.
It is notoriously difficult to study population interactions among highly mobile animals that cannot be meaningfully confined to experimental plots of limited size. For example, migratory water birds are believed to suffer from competition with resident fish populations for shared food resources. While observational evidence in support of this hypothesis is accumulating, replicated experiments addressing this issue at the proper spatial scale are lacking. Here, we report from a replicated whole-system experiment in which we stocked large (0.07 km2), shallow (< or =2.5 m deep), highly eutrophic ponds in the bird protection area "Ismaninger Speichersee mit Fischteichen" with different densities of carp and assessed the responses of water birds and their food resources during summer over several years. In all years, the biomasses of benthic macroinvertebrates, macroalgae, and macrophytes as well as the densities of herbivorous, carnivorous, and omnivorous water birds were reduced in carp ponds compared to fishless ponds. The negative effects of carp on food resources and on the numbers of water birds feeding in carp ponds increased over the season (May-September) and were stronger at high than at low stocking densities of carp. Consequently, differences in resource densities between ponds with and without carp increased, and the ranking of ponds with respect to resource densities became more predictable over the season. These factors may have contributed to a seasonal improvement of the birds' abilities to track resource densities across ponds, as suggested by tight correlations of bird numbers on ponds with resource densities late, but not early, in the season.  相似文献   
67.
68.
Mandatory or voluntary reductions in ship speed are a common management strategy for reducing deleterious encounters between large ships and large whales. This has produced strong resistance from shipping and marine transportation entities, in part because very few studies have empirically demonstrated whether or to what degree ship speed influences ship-whale encounters. Here we present the results of four years of humpback whale sightings made by observers aboard cruise ships in Alaska, representing 380 cruises and 891 ship-whale encounters. Encounters occurred at distances from 21 m to 1000 m (x = 567 m) with 61 encounters (7%) occurring between 200 m and 100 m, and 19 encounters (2%) within 100 m. Encounters were spatially aggregated and highly variable across all ship speeds. Nevertheless a Bayesian change-point model found that the relationship between whale distance and ship speed changed at 11.8 knots (6.1 m/s) with whales encountering ships, on average, 114 m closer when ship speeds were above 11.8 knots. Binning encounter distances by 1-knot speed increments revealed a clear decrease in encounter distance with increasing ship speed over the range of 7-17 knots (3.6-8.7 m/s). Our results are the first to demonstrate that speed influences the encounter distance between large ships and large whales. Assuming that the closer ships come to whales the more likely they are to be struck, our results suggest that reduced ship speed may be an effective management action in reducing the probability of a collision.  相似文献   
69.
ABSTRACT

The sustainable city of the future is typically envisioned as smart, creative and disruptive, assuming that urban and local sustainability is achieved through new technology and innovation. However, considering that the built environments of our cities and surroundings are highly durable, there is also a need to focus on how resources brought from the past – histories, artefacts and places – may be used for promoting urban sustainability. We label this a “deep city” perspective on urban and local transformation. By looking at Røros, a World Heritage Site in central Norway with a dense and historic wooden urban centre, we investigate how its heritage protection facilitates the maintenance of a compact urban centre. We hold that a shared sense of place – the deepness– may serve as a resource against unsustainable sprawl and mall-oriented development.  相似文献   
70.
Climatic records from equatorial eastern Africa and subtropical southern Africa have shown that both temperature and the amount of rainfall have varied over the past millennium. Moreover, the rainfall pattern in these regions varied inversely over long periods of time. Droughts started abruptly, were of multi-decadal to multi-centennial length and the changes in the hydrological budget were of large amplitude. Changing water resources in semi-arid regions clearly must have regional influences on both ecological and socio-economic processes. Through a detailed analysis of the historical and paleoclimatic evidence from southern and eastern Africa covering the past millennium it is shown that, depending on the vulnerability of a society, climatic variability can have an immense impact on societies, sometimes positive and sometimes disastrous. Therefore, the interconnected issue of world ecosystem and social resilience is the challenge for decision-makers if sustainable development is to be reached on global and local levels.  相似文献   
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