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排序方式: 共有402条查询结果,搜索用时 62 毫秒
1.
There is an assumption that with the disintegration of the Soviet Union, the Second World ceased to exist. Yet the demise of the Communist bloc as a geopolitical reality did not mean that it stopped exerting a defining influence over how people think and behave. This article examines how the postsocialist state in Kazakhstan deals with potential crises such as earthquakes and the extent to which the Soviet legacy still shapes intellectual debates, state structures, and civil society organisations in in that country. Drawing on fieldwork and interviews, this paper re-examines the Second World in its historical context and re-establishes it as a conceptual framework for considering disaster risk reduction in the former Soviet bloc. It argues that it is essential to pay attention to this legacy in Kazakhstan both in policy and practice if earthquake risk reduction is to be made more effective. 相似文献
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Laser welding is used for joining advanced high strength steels (AHSS) to improve formability and performance. In this paper, the geometric variability observed in the fusion zones and heat affected zones of several combinations of AHSS (different types, coatings and thicknesses), which were butt welded using a Trumpf TRUDISK 6000® Yb:YAG laser beam, is presented. The surface texture parameters such as roughness and waviness of laser welds were also measured and correlated with geometric variability. Results indicate that although high quality welds with minimal defects can be obtained using the Yb:YAG laser welding process, there is considerable variation in both the shape and the dimensions of weld zones. The variability increased with an increase in thickness differentials between the sheets being welded. Analysis of the top of the weld surfaces also suggested that aluminum coating on USIBOR samples contributes significantly to increased roughness. An increase in laser power coupled with corresponding increase in welding speed did not impact variability. A fair correlation between the surface roughness and weld region variability exists, although this needs further study. 相似文献
4.
Adam Peters Peter Simpson Graham Merrington Chris Schlekat Emily Rogevich-Garman 《Environmental science and pollution research international》2014,21(1):193-204
A field-based evaluation of the biological effects of potential nickel (Ni) exposures was conducted using monitoring data for benthic macroinvertebrates and water chemistry parameters for streams in England and Wales. Observed benthic community metrics were compared to expected community metrics under reference conditions using RIVPACS III+?software. In order to evaluate relationships between Ni concentrations and benthic community metrics, bioavailable Ni concentrations were also calculated for each site. A limiting effect from Ni on the 90th percentile of the maximum achievable ecological quality was derived at “bioavailable Ni” exposures of 10.3 μg l?1. As snails have been identified as particularly sensitive to nickel exposure, snail abundance in the field in response to nickel exposure, relative to reference conditions, was also analysed. A “low effects” threshold for snail abundance based on an average of spring and autumn data was derived as 3.9 μg l?1 bioavailable Ni. There was no apparent effect of Ni exposure on the abundance of Ephemeroptera (mayflies), Plecoptera (stoneflies) or Tricoptera (caddisflies) when expressed relative to a reference condition within the range of “bioavailable Ni” exposures observed within the dataset. Nickel exposure concentrations co-vary with the concentrations of other stressors in the dataset, and high concentrations of Ni are also associated with elevated concentrations of other contaminants. 相似文献
5.
Gregory S. Piorkowski Rob C. Jamieson Lisbeth Truelstrup Hansen Greg S. Bezanson Chris K. Yost 《Environmental monitoring and assessment》2014,186(1):277-291
Escherichia coli can persist in streambed sediments and influence water quality monitoring programs through their resuspension into overlying waters. This study examined the spatial patterns in E. coli concentration and population structure within streambed morphological features during baseflow and following stormflow to inform sampling strategies for representative characterization of E. coli populations within a stream reach. E. coli concentrations in bed sediments were significantly different (p?=?0.002) among monitoring sites during baseflow, and significant interactive effects (p?=?0.002) occurred among monitoring sites and morphological features following stormflow. Least absolute shrinkage and selection operator (LASSO) regression revealed that water velocity and effective particle size (D 10) explained E. coli concentration during baseflow, whereas sediment organic carbon, water velocity and median particle diameter (D 50) were important explanatory variables following stormflow. Principle Coordinate Analysis illustrated the site-scale differences in sediment E. coli populations between disconnected stream segments. Also, E. coli populations were similar among depositional features within a reach, but differed in relation to high velocity features (e.g., riffles). Canonical correspondence analysis resolved that E. coli population structure was primarily explained by spatial (26.9–31.7 %) over environmental variables (9.2–13.1 %). Spatial autocorrelation existed among monitoring sites and morphological features for both sampling events, and gradients in mean particle diameter and water velocity influenced E. coli population structure for the baseflow and stormflow sampling events, respectively. Representative characterization of streambed E. coli requires sampling of depositional and high velocity environments to accommodate strain selectivity among these features owing to sediment and water velocity heterogeneity. 相似文献
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Changes in Streambed Composition in Salmonid Spawning Habitat of the Elwha River during Dam Removal 下载免费PDF全文
Roger J. Peters Martin Liermann Michael L. McHenry Paul Bakke George R. Pess 《Journal of the American Water Resources Association》2017,53(4):871-885
One uncertainty associated with large dam removal is the level of downstream sediment deposition and associated short‐term biological effects, particularly on salmonid spawning habitat. Recent studies report downstream sediment deposition following dam removal is influenced by proximity to the source and river transport capacity. The impacts of dam removal sediment releases are difficult to generalize due to the relatively small number of dam removals completed, the variation in release strategies, and the physical nature of systems. Changes to sediment deposition and associated streambed composition in the Elwha River, Washington State, were monitored prior to (2010‐2011) and during (2012‐2014) the simultaneous removal of two large dams (32 and 64 m). Changes in the surface layer substrate composition during dam removal varied by year and channel type. Riffles in floodplain channels downstream of the dams fined and remained sand dominated throughout the study period, and exceeded levels known to be detrimental to incubating salmonids. Mainstem riffles tended to fine to gravel, but appear to be trending toward cobble after the majority of the sediment was released and transported through system. Thus, salmonid spawning habitats in the mainstem appear to have been minimally impacted while those in floodplain channels appear to have been severely impacted during dam removal. 相似文献
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Experiencing nature and enjoying natural amenities have long been identified as key motives for rural second home tourism. However, the more people travel and spend time in the natural environment, the more it is disturbed by their actions and activities. In this paper, we examine how people perceive the environmental impacts of rural second home tourism and how they justify their views. The study focuses on Finland where rural second homes are widespread. Analysis is based on a questionnaire survey conducted among Finns in 2012 (n?=?1189). Responses from different groups of respondents (second home owners, regular users of second homes and non-users) are quantitatively and qualitatively analysed. The results indicate that the Finnish respondents generally think that second home tourism poses some degree of harmful environmental impacts. However, it is the second home owners who are least worried about these environmental impacts. They generally justify their opinions using a “place-related” perspective, that is, by referring to their own experiences and actions at the cottage site. In contrast, the non-users see environmental impacts more often from a broader perspective by referring to the wider environmental interconnections with second home tourism. In our discussion, we introduce the notions of place-based (relative) and phenomenon-based (relational) environmental perceptions as a potential framework for future research on this topic. In mitigating the increasing environmental impacts of second home tourism, understanding the environmental perceptions and awareness of second home owners and users is crucial to be successful in mobilising sustainable options and environmental governance. 相似文献
9.
Research and application of method of oxygen isotope of inorganic phosphate in Beijing agricultural soils 总被引:1,自引:0,他引:1
Liyan Tian Qingjun Guo Yongguan Zhu Huijun He Yunchao Lang Jian Hu Han Zhang Rongfei Wei Xiaokun Han Marc Peters Junxing Yang 《Environmental science and pollution research international》2016,23(23):23406-23414
Phosphorus (P) in agricultural ecosystems is an essential and limited element for plants and microorganisms. However, environmental problems caused by P accumulation as well as by P loss have become more and more serious. Oxygen isotopes of phosphate can trace the sources, migration, and transformation of P in agricultural soils. In order to use the isotopes of phosphate oxygen, appropriate extraction and purification methods for inorganic phosphate from soils are necessary. Here, we combined two different methods to analyze the oxygen isotopic composition of inorganic phosphate (δ18OP) from chemical fertilizers and different fractions (Milli-Q water, 0.5 mol L?1 NaHCO3 (pH = 8.5), 0.1 mol L?1 NaOH and 1 mol L?1 HCl) of agricultural soils from the Beijing area. The δ18OP results of the water extracts and NaHCO3 extracts in most samples were close to the calculated equilibrium value. These phenomena can be explained by rapid P cycling in soils and the influence of chemical fertilizers. The δ18OP value of the water extracts and NaHCO3 extracts in some soil samples below the equilibrium value may be caused by the hydrolysis of organic P fractions mediated by extracellular enzymes. The δ18OP values of the NaOH extracts were above the calculated equilibrium value reflecting the balance state between microbial uptake of phosphate and the release of intracellular phosphate back to the soil. The HCl extracts with the lowest δ18OP values and highest phosphate concentrations indicated that the HCl fraction was affected by microbial activity. Hence, these δ18Op values likely reflected the oxygen isotopic values of the parent materials. The results suggested that phosphate oxygen isotope analyses could be an effective tool in order to trace phosphate sources, transformation processes, and its utilization by microorganisms in agricultural soils. 相似文献
10.
Anthropogenic environmental impacts can disrupt the sensory environment of animals and affect important processes from mate choice to predator avoidance. Currently, these effects are best understood for auditory and chemosensory modalities, and recent reviews highlight their importance for conservation. We examined how anthropogenic changes to the visual environment (ambient light, transmission, and backgrounds) affect visual communication and camouflage and considered the implications of these effects for conservation. Human changes to the visual environment can increase predation risk by affecting camouflage effectiveness, lead to maladaptive patterns of mate choice, and disrupt mutualistic interactions between pollinators and plants. Implications for conservation are particularly evident for disrupted camouflage due to its tight links with survival. The conservation importance of impaired visual communication is less documented. The effects of anthropogenic changes on visual communication and camouflage may be severe when they affect critical processes such as pollination or species recognition. However, when impaired mate choice does not lead to hybridization, the conservation consequences are less clear. We suggest that the demographic effects of human impacts on visual communication and camouflage will be particularly strong when human‐induced modifications to the visual environment are evolutionarily novel (i.e., very different from natural variation); affected species and populations have low levels of intraspecific (genotypic and phenotypic) variation and behavioral, sensory, or physiological plasticity; and the processes affected are directly related to survival (camouflage), species recognition, or number of offspring produced, rather than offspring quality or attractiveness. Our findings suggest that anthropogenic effects on the visual environment may be of similar importance relative to conservation as anthropogenic effects on other sensory modalities. 相似文献