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91.
When Hurricane Iniki struck the Hawaiian Islands in September 1992, it provided a rare opportunity to examine the immediate effects of a hurricane on two intertidal benthic communities off the reefs of O'ahu, Hawai'i. The Niu Beach site contained large, obvious aggregations of the tube building polychaete Diopatra dexiognatha, and the Wailupe Beach site was without obvious tubiculous fauna at the surface. Ten replicate sediment cores were taken before and after the hurricane with a 7.6 cm PVC corer and organisms were identified to family and enumerated. There were no substantial depletions or loss of taxa after the hurricane. Oligochaetes were the most dominant taxa pre-and post-hurricane. The abundance of all dominant polychaete families increased post-hurricane. The three most abundant polychaetes were capitellids and D. dexiognatha (Onuphidae) at Niu Beach and Pygospio muscularis (Spionidae) at Wailupe Beach. We suggest that D. dexiognatha and P. muscularis help stabilize the sediments since they both form dense tube mats while capitellids and oligochaetes are considered highly adaptive surface burrowers that can take advantage of newly disturbed sediments. Overall, there was no substantial effect observed on the intertidal fauna exposed to this severe disturbance. It is suggested here that invertebrate communities in this area are adapted to survive and thrive in high-energy environments and possibly benefit from dense aggregations of tube building polychaetes.  相似文献   
92.
We present the 2320-2050 cm-1 (4.31-4.88 micrometers) infrared spectra of 16 solid-state nitriles, isonitriles, and related compounds in order to facilitate the assignment of absorption features in a spectral region now becoming accessible to astronomers for the first time through the Infrared Space Observatory (ISO). This frequency range spans the positions of the strong C triple bond N stretching vibration of these compounds and is inaccessible from the ground due to absorption by CO2 in the terrestrial atmosphere. Band positions, profiles, and intrinsic strengths (A values) were measured for compounds frozen in Ar and H2O matrices at 12 K. The molecular species examined included acetonitrile, benzonitrile (phenylcyanide), 9-anthracenecarbonitrile, dimethylcyanamide, isopropylnitrile (isobutyronitrile), methylacrylonitrile, crotononitrile, acrylonitrile (vinyl cyanide), 3-aminocrotononitrile, pyruvonitrile, dicyandiamide, cyanamide, n-butylisocyanide, methylisocyanoacetate, diisopropylcarbodiimide, and hydrogen cyanide. The C triple bond N stretching bands of the majority of nitriles fall in the 2300-2200 cm-1 (4.35-4.55 micrometers) range and have similar positions in both Ar and H2O matrices, although the bands are generally considerably broader in the H2O matrices. In contrast, the isonitriles and a few exceptional nitriles and related species produce bands at lower frequencies spanning the 2200-2080 cm-1 (4.55-4.81 micrometers) range. These features also have similar positions in both Ar and H2O matrices, and the bands are broader in the H2O matrices. Three of the compounds (pyruvonitrile, dicyandiamide, and cyanamide) show unusually large shifts of their C triple bond N stretching frequencies when changing from Ar to H2O matrices. We attribute these shifts to the formation of H2O:nitrile complexes with these compounds. The implications of these results for the identification of the 2165 cm-1 (4.62 micrometers) "XCN" interstellar feature and the 4550 cm-1 (2.2 micrometers) feature of various objects in the solar system are discussed.  相似文献   
93.
We have discovered a new IR emission feature at 1905 cm-1 (5.25 microns) in the spectrum of BD +30 degrees 3639. This feature joins the family of well-known IR emission features at 3040, 2940, 1750, 1610, "1310," 1160, and 890 cm-1 (3.3, 3.4, 5.7, 6.2, "7.7," 8.6, and 11.2 microns). The origin of this new feature is discussed and it is assigned to an overtone or combination band involving C-H bending modes of polycyclic aromatic hydrocarbons (PAHs). Laboratory work suggests that spectral studies of the 2000-1650 cm-1 (5.0-6.1 microns) region may be very useful in elucidating the molecular structure of interstellar PAHs. The new feature, in conjunction with other recently discovered spectral structure, suggests that the narrow IR emission features originate in PAH molecules rather than large carbon grains. Larger species are likely to be the source of the broad underlying "plateaus" seen in many of the spectra.  相似文献   
94.
卫星遥感北京大雾气候分布特征及成因分析初探   总被引:1,自引:0,他引:1  
利用极轨气象卫星资料,结合地面能见度资料,对北京市2001-2005年的大雾信息进行了处理分析,生成了多种大雾遥感信息产品.利用处理结果,对2001-2005年北京地区大雾频次分布特点进行了分析.其中卫星遥感2001-2005年北京地区大雾天数统计图反映了近五年来北京市不同地区大雾出现的频次,卫星遥感各季节大雾天数统计图反映了不同季节北京地区大雾分布的时空变化特点,卫星遥感大雾程度指数(像元级空间尺度)反映了北京市不同区县单位面积大雾出现的频次差异.同时,根据卫星遥感大雾分析结果、形成大雾的最主要气象要素资料(地面温、压、湿)、地理信息、高程数据等,还对近5年北京市不同季节不同地区大雾分布的特征、时空变化的气象成因和主要大雾类型(平流雾、辐射雾)进行了分析.综合各种分析结果,北京市大雾分布存在以下几个特点:第一,北京地区的大雾虽一年四季均有发生,但存在明显的季节性特点,以夏秋季偏多,以冬春季偏少;第二,大雾频发区主要位于北京市东南部和中东部偏北的部分地区.西部相对较少;第三,受地形和地面环境流场影响,东南部大雾以平流雾为主,北部和西北部地区以辐射雾为主;第四,辐射雾发生频次与下垫面类型有密切关系,城市热岛对大雾的影响明显.  相似文献   
95.
A Greek oil-tanker ran aground, resulting in a huge oil spill along the costal areas of Karachi, Pakistan. The purpose of this study was to assess the lung function and follow up change after one year in subjects exposed to crude oil spill in sea water. It was a cross sectional study with follow up in 20 apparently healthy, non-smoking, male workers, who were exposed to a crude oil spill environment during oil cleaning operation. The exposed group was matched with 31 apparently healthy male control subjects. Pulmonary function test was performed using an electronic Spirometer. Subjects exposed to polluted air have significant reduction in forced vital capacity (FVC), forced expiratory volume in first second (FEV(1)), forced expiratory flow (FEF(25-75%)) and maximum voluntary ventilation (MVV) compared to their matched controls. This impairment was reversible and lung functions parameters were improved when the subjects were withdrawn from the polluted air environment.  相似文献   
96.
本文描述了沙特阿拉伯油田3种新技术应用实例;三维地震,水平井,多侧向钻井,结果表明;(1)应用三维地震使油田探边更准确,油藏描述更精细,更准确的油藏体积预测可以制定可靠的油田开发和生产目标,对沉积相和饱和度范围等油藏描述更精细有助于降低油田开发成本,高效进行油藏经营管理。(2)水平井和大斜度井有利于开发;钻垂直井没有经济效益的低渗透致密油藏,圈闭在有随机焦油少充填的油藏中油带及顶层油,底水之止滞留  相似文献   
97.
98.
1973—2018年珠江三角洲海岸线时空演变分析   总被引:1,自引:0,他引:1       下载免费PDF全文
通过遥感和GIS技术获取1973—2018年的Landsat TM/OLI遥感影像为数据源,结合地理背景资料,分析45 a来珠江三角洲地区海岸线时空演变情况。结果表明:珠江三角洲地区海岸线变迁显著,大量的淤泥质岸线转变为城镇工业岸线和港口岸线,珠江三角洲地区岸线人工化指数不断上升,岸线类型朝向多元化方向发展,岸线总长度和分形维数不断增加,港口建设、滨海工业区、围垦填海等是岸线长度和分形维数增加的主要因素;海岸线演变呈现明显的区域特征,变化较大区域主要集中在深圳大鹏湾、广州南沙和珠海斗门;从岸线开发利用主体结构上看,各大岸区都出现了不同类型的变化趋势,城镇工业岸线与港口岸线取代自然岸线成为各区海岸线的主体类型;各地区开发利用强度不断上升,其中深圳市开发强度增速最快,社会活动和区位政策是引起岸线演变的主要驱动因素。  相似文献   
99.
城市地表热环境遥感监测指标研究及应用   总被引:6,自引:0,他引:6  
遥感已成为城市热环境监测的重要手段,但仅依靠城市地表温度(或亮温)仍难以定量分析城市热环境的时空变化。文章提出了城市热环境遥感监测的3个指标:热岛强度、热场强度指数和热岛比例指数,并利用2年的MODIS地表温度产品与FY-3A/MERSI卫星资料对北京地区进行了热环境遥感监测应用与分析。结果表明:上述3个热环境遥感监测指标在城市热岛监测中具有指示意义,能有效监测北京城市热岛的强弱和变化,对开展城市热环境监测气象业务具有积极意义。  相似文献   
100.
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