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41.
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笔者重点分析了哈尔滨河床冲积物的粒度组成,结合沙尘沉降物的粒度组成,论述了裸露河床冲积物对沙尘天气的影响。河床冲积物及沙尘沉降物粒度分析结果显示,裸露河床冲积物粒径大于63μm的颗粒占84%以上,而小于63μm粒径的颗粒很少,小于10μm的颗粒微乎其微;沙尘沉降物中小于63μm的粉粘颗粒含量在90%以上。对河床冲积物而言,无论是砂级别的粗颗粒物质还是粉粘级别的细颗粒物质都与沙尘沉降物的粒度无相关性,对沙尘暴物质组成没有影响或影响很小。受砂级别的粗颗粒物质扬起高度和搬运距离的限制,沙尘暴发生时,裸露河床中的冲积物颗粒不会被远距离搬运而影响到整个哈尔滨地区,真正影响整个哈尔滨地区的沙尘物质是小于63μm的粉砂级别的颗粒,特别是小于10μm的粉尘。笔者认为对哈尔滨沙尘天气产生重大影响的是含有大量细颗粒物质的城市地表土和建筑土等,这些地域是防止沙尘天气的重点治理区域。 相似文献
43.
Mohamed?IsmailEmail author Tadashi?Kimura Yumiko?Suzuki Makoto?Tsuchiya 《Journal of Oceanography》2005,61(3):631-644
Total mass flux, size distribution of sediment particles and some chemical components such as total carbon (TC), total nitrogen (TN) and calcium carbonate (CaCO3) were monitored monthly using a multi-cup sediment traps at seven coral reef sites (6 reef flat and 1 reef slope) of the Marine Protected Areas around Ishigaki, Kohama, Kuroshima and Iriomote Islands in the southern Ryukyus, Japan from September 2000 to September 2001. The size distribution of trapped sediments revealed mostly uni-modal fine sand to mud in the reef flat and gravelly to coarse sand in the reef slope. The total mass flux ranged between 0.54 to 872 gm−2d−1, and showed a pronounced seasonality (high in summer-autumn and low in spring) at each site, which was consistent with the rainfall and typhoon regime. Exceptionally high values were observed on the reef slope (Iriomote) in February–March 2001 (1533 gm−2d−1) owing to a large amount of bottom sediment re-suspension. On the reef flat (Todoroki South and North; Ishigaki), values obtained in July–August 2001 (872 gm−2d−1) and August–September 2001 (800 gm− 2d−1) indicate the high terrestrial discharge from Todoroki River. Trapped sediment particles consist of CaCO3 (1.2–27.1%) and a non-carbonate fraction (98.8–72.9%), which contains total carbon (4.9–26%), carbonate carbon (CO2-C) (0.2–3.1%) and non-carbonate carbon (NC-C) (7.9–25.6%). Total nitrogen content was in the range 0.02–0.48%. TN is contained mainly in the carbonate fraction and NC-C may be contained in the non-carbonate fraction. The low TN/OC ratio of the trapped sediments suggests that they were mostly of terrestrial origin and that both fractions migrated. The high total mass flux derived from Todoroki River exceeded the threshold at which a lethal effect on coral community is caused. The results stress the importance of conducting seasonal studies of sedimentation over more than one year and at more than one location in south Japan coral reef ecosystems to gain an understanding of the processes controlling the total mass fluxes and their nutrients content, also to develop an awareness of how to prevent the damage of coral reef ecosystems and, if it does occur, to allow mitigation measures to be undertaken. 相似文献
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海洋生态环境监测的指标体系研究 总被引:1,自引:0,他引:1
本文在总结国内外各种海洋生态监测方法的基础上,构建生物分布指数、生物暴露指数和生物反应指数,并由此确定生态质量总指教。生态质量总指数可以综合反映特定海洋环境的生物群落特征,典型污染物在生物体内的蓄积特征以及生物体对环境污染的生理生化反应特征,因此可以应用于近岸海洋环境质量的生态监测。 相似文献
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47.
Edward F. Roseman Christine A. Tomichek Tracy Maynard Jennifer A. Burton 《Journal of Sea Research》2005,53(4):309-318
Grubby (Myoxocephalus aenaeus, Cottidae) is a common benthic fish of inshore waters and estuaries of eastern Long Island Sound; however, little information exists on their life history or population demographics. This study utilised a long-term data series (1976–2002) to assess grubby life history and population demographics and explores trends in the Niantic River and Niantic Bay populations. In addition, we examined the age, size, and fecundity of adult grubby in 2001–02 to determine the population characteristics in the region. Mean grubby catch per unit effort (CPUE) in Niantic Bay ranged from 0.4 per trawl in 1976 to 2.9 per trawl in 1984 while river CPUE ranged from 0.4 per trawl in 1977 to 7.6 per trawl in 1989. Catch of grubby in bottom trawls varied seasonally with highest CPUE occurring in winter. Highest entrainment of grubby larvae occurred in 2001 while the lowest entrainment observed was in 1991. Four age classes, 0+ through III+, were derived from otolith analysis (N = 51) although length frequency analysis suggested the possibility of older fish in the population. The total number of eggs in ovaries ranged from 286 to 16 451 for grubby (N = 64) between 52 mm and 155 mm TL. Results of this study indicated a decline in abundance of adult grubby over the 26-year period, possibly related to concurrent declines in eelgrass (Zostera marina) abundance and/or increased water temperature. 相似文献
48.
结合近年来参与有关水下工程检测和项目监理的实践体验 ,从总结水下工程项目的基本特征着手 ,分析了水下工程项目监理的主要任务 ,并结合对于实施水下工程项目监理必备装备条件的探讨 ,介绍了国内外现有水下监测技术装备的开发应用状况 相似文献
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Bathymetry of the Tonga Trench and Forearc: a map series 总被引:1,自引:0,他引:1
Wright Dawn J. Bloomer Sherman H. MacLeod Christopher J. Taylor Brian Goodlife Andrew M. 《Marine Geophysical Researches》2000,21(5):489-512
Four new bathymetric maps of the Tonga Trench and forearc between 14 °S and 27 °S display the important morphologic and structural features of this dynamic convergent margin. The maps document a number of important geologic features of the margin. Major normal faults and fault lineaments on the Tonga platform can be traced along and across the upper trench slope. Numerous submarine canyons incised in the landward slope of the trench mark the pathways of sediment transport from the platform to mid- and lower-slope basins. Discontinuities in the trench axis and changes in the morphology of the landward slope can be clearly documented and may be associated with the passage and subduction of the Louisville Ridge and other structures on the subducting Pacific Plate. Changes in the morphology of the forearc as convergence changes from normal in the south to highly-oblique in the north are clearly documented. The bathymetric compilations, gridded at 500- and 200-m resolutions and extending along 500 km of the landward trench slope and axis, provide complete coverage of the outer forearc from the latitude of the Louisville Ridge-Tonga Trench collision to the northern terminus of the Tonga Ridge. These maps should serve as a valuable reference for other sea-going programs in the region, particularly the Ocean Drilling Program (ODP) and the National Science Foundation MARGINS initiative. 相似文献