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991.
以宁波市为研究对象,利用1984─2010年间冬、夏各5景Landsat TM/ETM+遥感影像数据进行地表温度反演,在此基础上使用热岛强度、热岛面积、景观格局指数综合分析了宁波城市化进程中城市热岛在冬、夏两季的演变趋势,得出如下结果,(1)强度方面,冬季平均热岛强度为1.57℃,夏季为8.67℃,夏季明显强于冬季;热岛强度在夏季呈增强趋势,在冬季呈变弱趋势。(2)热岛面积方面,在冬季,平均89%的建成区受热岛效应的影响,而在夏季,该比例为98%。无论冬夏,热岛面积均随城市化的发展持续增加。(3)数量方面,热岛景观在冬季以低等级热岛斑块为主,占热岛面积的96%左右,夏季以中、高等级热岛斑块为主,比例约为热岛面积的92%。无论冬夏高等级热岛斑块个数均随着城市化进程显著增加。(4)形态方面,无论冬夏主要热岛景观类型乃至整个热岛的斑块形状均变得更加复杂。(5)结构方面,热岛景观在冬季总体上逐渐破碎化,各类景观趋向均匀,多样性增加。在夏季则逐渐聚集,逐步向以高等级斑块为主导的格局方向发展,多样性降低。(6)空间分布方面,随着城市化进展,冬夏两季热岛景观斑块都经历了数量增加、等级升高的变化。冬季在北仑的宁波经济技术开发区形成了两个热点区,夏季在三江口周边、甬江口两岸以及经济技术开发区形成了三大高温片区。利用多指标综合分析可以更加全面的反映城市热岛的演变规律,为减缓城市热岛效应提供理论依据。 相似文献
992.
O.J. Owen J.P. Alawa S.N. Wekhe A.O. Aniebo E.M. Ngodigha A.O. Amakiri 《毒物与环境化学》2013,95(6):1193-1196
An investigation was carried out to determine the microbial load in poultry litter used as feed supplement in rabbit diets. Before heat treatment by deep stacking the poultry litter, samples of the litter were collected to assay for microbial load at the Microbiology Laboratory of the Rivers State University of Science and Technology, Port Harcourt, Nigeria. Results obtained showed that before heat-treating the poultry litter, Escherichia coli, Salmonella, Mycobacterium, Clostridium and Staphylococcus were isolated at 41, 37, 37, 41 and 42°C, respectively. The results obtained also indicate that no pathogen was isolated after heat treatment of between 40 and 55°C for 21 days. This study justifies the suitability of using poultry litter as a feed supplement. 相似文献
993.
The effects of sodium arsenite exposure from postnatal day (PND) 1 to PND 14 on Leydig cells of Wistar rat testes were investigated at PND 15 and 21. Gross morphometric observations of testes did not reveal a significant change in the numerical density and volume of the testes in exposed animals compared to controls either at PND 15 or 21. However, there was significant decrease in testicular weight at PND 21 in treated animals. Measurement of nuclear area of Leydig cells revealed a decrease in nuclear area of these cells in exposed groups at PND 15 and 21. A significant decrease in the total number of Leydig cells was apparent at PND 21 in the treated group. The observations of the present study are indicative of adverse effects on rat testes Leydig cells following exposure to low doses of sodium arsenite during critical window periods. The persistence of these observations at PND 21 is suggestive of irreversible damage to testicular tissue. 相似文献
994.
降温服是一种应用于高温环境条件下的个体防护设备。根据深矿井热害治理需求,提出用人体降温服对人体直接降温的个体防护方法。结合降温服的降温原理和分类,对个体降温服国内外研究现状及其在矿井热害治理中的可能应用进行了综述和评价分析。为在深矿井热害治理中有针对性的研究、设计和应用矿用人体降温服提供参考。 相似文献
995.
在三峡库区香溪河的支流高岚河库湾修建生物浮岛,研究生物浮岛对三峡库区典型支流库湾水质和浮游藻类的影响.结果表明,高岚河水质处于中营养型-轻度富营养型水平.8月藻类大量生长期间,浮岛区水体Chl-a、DO和CODMn含量低于对照区,NH4+-N含量高于对照区.浮岛植物对TN负荷的去除效果由高到低依次为美人蕉(Canna indica)、风车草(Cyperus alternifolius)、菖蒲(Pontederia cordata)和梭鱼草(Acorus calamus),对TP负荷的去除效果由高到低依次为美人蕉、风车草、梭鱼草和菖蒲.在浮岛区和对照区共发现藻类7门31属,4月以绿藻和硅藻为主,8月以蓝藻为主.浮岛区和对照区藻类种群结构无明显差异,但4和8月浮岛区藻类生物量明显低于对照区. 相似文献
996.
Cynthia Rosenzweig William D. Solecki Lily Parshall Mark Chopping Gregory Pope Richard Goldberg 《Environmental Hazards》2013,12(1):51-62
Climate change caused by increased anthropogenic emissions of carbon dioxide (CO2) and other greenhouse gases is a long-term climate hazard with the potential to alter the intensity, temporal pattern, and spatial extent of the urban heat island (UHI) in metropolitan regions. Particular meteorological conditions—including high temperature, low cloud cover, and low average wind speed—tend to intensify the heat island effect. Analyses of existing archived climate data for the vicinities of Newark and Camden, New Jersey indicate urban to suburban/rural temperature differences over the previous half-century. Surface temperatures derived from a Landsat thermal image for each site were also analyzed for spatial patterns of heat islands. Potential interactions between the UHI effect and projected changes in temperature, wind speed, and cloud cover are then examined under a range of climate change scenarios, encompassing different greenhouse gas emissions trajectories. The scenarios include those utilized in the Metropolitan East Coast Regional Assessment of Climate Variability and Change and the A2 and B2 scenarios of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES). The UHI effect was detected in Newark and Camden in both satellite surface-temperature and meteorological station airtemperature records. The average difference in urban—nonurban minimum temperatures was 3.0 °C for the Newark area and 1.5 °C for Camden. Extrapolation of current trends and the selected global climate models (GCMs) project that temperatures in the case study areas will continue to warm in the current century, as they have over the past half-century. An initial analysis of global climate scenarios shows that wind speed may decline, and that cloud cover may increase in the coming decades. These generally small countervailing tendencies suggest that urban—nonurban temperature differences may be maintained under climate change. Overall warmer conditions throughout the year may extend the spatial and temporal dimensions of the urban-suburban heat complex. The incidence of heat-related morbidity and mortality are likely to increase with interactions between the increased frequency and duration of heat waves and the UHI effect. Camden and Newark will likely be subjected to higher temperatures, and areas experiencing UHI-like conditions and temperature extremes will expand. Thus, urban heat island-related hazard potential is likely to increase in a warmer climate. 相似文献
997.
《Environmental Hazards》2013,12(2):49-62
Abstract This paper sets out an examination of natural disaster amongst small island developing states (SIDS), and presents a framework for assessing the interaction of global pressures and local dynamics in the production of human vulnerability. Change at the global level is found to be a source of new opportunities as well as constraints on building local resilience to natural disaster. Much depends on the orientation of the state in global economic and political systems. The United Nations is a key global actor with relevance to shaping vulnerabilityin island states, and the impact of the UN Decade for Natural Disaster Reduction is reviewed. It is concluded that this is a critical time for SIDS which must contend with ongoing developmental pressures in addition to growing pressures from risks associated with global environmental change and economic liberalisation that threaten their physical and economic security. 相似文献
998.
煤炭在构造应力的作用下会产生不同形状的裂隙,不同的裂隙会对煤层内的流动与传热产生影响。以阜新市高德煤矿为例,建立二维物理模型,采用两区域方法构造控制方程组,运用计算机软件对四种裂隙下煤层的流场和温度场进行数值计算。计算结果表明:不同裂隙对煤层流场的影响主要在空气流动侧,对煤层区域影响很小;不同裂隙对煤层温度场的影响主要在裂隙界面上,对外界空气和煤层内部的影响均很小;不同裂隙条件下煤层壁面平均努谢尔特数曲线的契合度随着瑞利数的增加而不断降低,相比标准界面,其他三种界面的煤层壁面平均努谢尔特数值基本一致。研究结果可为煤矿的安全开采提供理论性指导。 相似文献
999.
B. L. Turner II 《Journal of Land Use Science》2016,11(6):689-697
ABSTRACTLand system science (LSS) has expanded its research focus from the drivers of land-use and -cover change primarily in rural wildlands to include the social-environmental consequences of this change, urban areas, and sustainability practice. Land system architecture, interacting with the landscape mosaic approach in ecology, offers a special niche for the entry of rural areas and wildlands into urban sustainability research through examinations of the composition and configuration of ‘cityscapes’. Given the fine-grain data requirements of heterogeneous cityscapes, emergent land architecture-mosaic approaches have largely explored the urban heat island (UHI) problem, a topic that links LSS with the interests of urban climatology, engineering, and planning in city morphology or geometry. The subtle distinctions in the treatment of land configuration between land architecture-mosaic approaches and urban morphology-geometry approaches are identified. Several examples of the land architecture-mosaic approach illustrate the understanding gained about the UHI problem as well as its complementarity with morphology-geometry approaches. This understanding provides insights about the design of urban areas at the parcel to neighborhood scales to ameliorate extreme temperatures, an issue of increasing concern for urban areas worldwide and consistent with the sustainability problems identified by such international programs as Future Earth. 相似文献
1000.