江苏北部废黄河口水下三角洲稳定性和深水港建设

废黄河口三角洲的演化主要表现为水下三角洲大面积的冲蚀和三角洲海岸线的夷平,形成了由—10m以深的平坦悔床、—5m～—10m问的水下斜坡和—5m以浅的近岸浅滩三个地貌单元构成的地形格局。—10m～—15m水下平台稳定,略有冲刷;而水下斜坡随着往复性潮流长轴与斜坡走向逐渐趋于一致,潮流侧向侵蚀弱化;近岸浅滩则表现为人工护岸条件下的有限下切。这为深水港口的建设提供了良好的近岸水深条件和相对稳定的水陆域环境。     

1961～2018年长白山区不同等级降水时空变化特征

在全球气候变化影响下,长白山区的降水量发生着显著的变化,降水强度也发生着不同程度的变化。明确长白山区不同等级降水的降水量和降水天数的变化趋势对于揭示长白山区水资源演变规律具有重要意义。本研究基于长白山区气象观测站点的逐日降水数据,选取不同等级降水指标,分析了1961～2018年长白山区不同等级降水时空变化特征。结果表明:近60年,长白山区年均降水量呈现不显著的下降趋势（?0.31 mm/a）,降水天数呈现显著的下降趋势（?0.16 mm/a）,平均降水强度呈现不显著的上升趋势。不同等级降水变化主要体现为:小雨、中雨和大雨年均降水量和降水天数呈现下降趋势,而暴雨年均降水量和降水天数呈现不显著的增加趋势。长白山区年均降水量和降水天数的减少主要受小雨、中雨和大雨降水量和降水天数的减少影响。不同季节降水变化方面,长白山区春冬季降水量呈增加趋势,夏季和秋季降水量和降水天数均呈下降趋势。     

加拿大地理学

今天,我愿意为我们杰出的来访者概述一下加拿大地理学的状况,讨论学科组织的一些主要特点,评论它的主要实力所在。尽管二十世纪初,在魁北克和安大略两地较老的大学里开设地理学课程,但直到1935年时,才在多伦多大学出现第一个独立的地理系。它是由在他的祖国澳大利亚巳经建立起杰出学术声誊,后来在芝加哥大学任教的格里菲思·泰勒(Griffth Taylor)教授创立的。     

甘肃省暴雨初探

着重分析甘肃省的暴雨特性与时空分布规律,列举了历年实测和调查最大点暴雨特征值,绘制了短历时暴雨～高程相关线、选配丁甘肃最大点暴雨外包线公式,对历年各时段最大暴雨均值、极值、Cv、Cs值等暴雨参数及典型暴雨时程分配和面时关系线等方面作了初步探讨。     

A retrospective analysis of trace metals, C, N and diatom remnants in sediments from the Mississippi River delta shelf

The development of oil and gas recovery offshore of the Mississippi River delta began in shallow water in the 1950s, expanded into deeper waters, and peaked in the 1990s. This area of the outer continental shelf (OCS) is the historical and present location of >90% of all US OCS oil and gas production and reserves. The juxtaposition of its 4000 producing platforms, recovering $10 billion yr(-1) of oil, gas and produced water in the same area where about 28% of the US fisheries catch (by weight) is made and near 40% of the US coastal wetlands, makes this an area worth monitoring for regional pollutant loading. This loading may come from several sources, including sources related to OCS development, but also from the Mississippi River watershed. In this context, any contaminant loading on this shelf may be neither detectable nor significant against a background of climatic or biological variability. We examined the sedimentary record for indicators of industrial byproducts from OCS oil and gas development and of industrial products entering via the Mississippi River, primarily using vanadium (V) and barium (Ba) concentrations normalized for aluminum (Al). Barium is primarily used in drilling muds in the form of barite, whereas V is an important strengthening component of metal alloys, including steel. The fluctuations in the accumulation of Ba, but not V, were coincidental with the presumed use of barite. The fluctuations in V concentration in the sediments were coincidental with the national consumption of V. Copper (Cu), cadmium (Cd) and zinc (Zn) concentrations in sediments fluctuate coincidentally with V, not Ba, thus indicating that the dominant source of these trace metals in offshore sediments were derived from riverine sources, and were not primarily from in situ industrial processes releasing them on the shelf. This is not to suggest that local site-specific contamination is not a significant management or health concern. The low oxygen (hypoxia; < or = 2 mg l(-1)) zone that consistently covers much of this continental shelf's bottom layer in summer is attributed to nitrate loading from the Mississippi River. Increased nitrogen loading from river to shelf stimulates diatom production whose loading to the bottom layer and subsequent metabolism results in oxygen being depleted faster than it is replaced. In the last two decades there has been an increased accumulation of organic matter in sediments near the mouth of the Mississippi River. This coupling between river water, surface water and bottom water has recently expanded westward of the Atchafalaya River delta towards the Texas coast. The accumulation of biogenic silica (BSi) and carbon in dated sediments is coincidental with variations in riverine nitrate flux, but not with either V or Ba accumulation rates. These analyses indicate that both OCS development and riverine sources exert strong influences on the sediment constituents offshore, and that these influences may be independent of one another.     

热点研究进展

介绍了热点的定义和基本特征并对关于热点研究需进一步探讨的问题进行了讨论。热点是地幔中长期和相对固定的热异常,它向海岛和大陆内部提供富集各种微量元素的岩浆,是地幔柱在地球表面的反映,主要以高热流、正重力异常、高地形隆起、剧烈火山活动为标志。热点在地球表面的分布是不均匀的,主要分布在南、北两个半球30°N~50°S的区域。关于地球上的热点个数,目前比较公认的观点是约有40~50个。最新的研究结果认为,根据热点的起源可以将全球热点大致分为两类,即传统意义上的热点(Classic hotspots)和构造成因的浅部热点(Notspots)。     

多波束系统全覆盖高精度测量的差分GPS配套技术

结合８６３计算海洋高技术领域开展的多波束系统试验测量所取得的差分ＧＰＳ配套技术成果，针对多汉束系统全覆盖高精度海洋底地形测量特点和在现有ＧＰＳ技术水平的基础上，提出共现场高精度深数据成图的差分ＧＰＳ配套技术的内容；主要包括远程高精度和高可靠性差分ＧＰＳ传输链的建立，保证高效率全覆盖测量的数字图形导航软件实现，提高测深数据坐标位置精度的定位数据优化处理步骤和提高测深数据本身精度的差分ＧＰＳ潮汐改正方     

“导流、挡沙、减淤”—长江口深水航道治理设计思想的新飞跃—纪念敬爱的窦国仁院士

长江口深水航道的治理 ,令多少人望而却步 ,又令多少人生发豪情并为之奋斗不息 !半个世纪以来 ,在党的领导下 ,聚集起一批科技精英 ,围绕长江口航道治理 ,殚精竭虑 ,摸索前进。在这支队伍中 ,窦国仁院士无疑是承上启下的一代中坚 ,是杰出的学术带头人。长江口水量充沛 ,又有大量的流域来沙。丰水多沙的流域特征和中等强度的潮汐作用 ,在广袤的长江下游冲积平原上塑造了规模巨大多级分汊的三角洲河口形态。在径流和潮汐的共同作用下 ,河口段河床冲淤多变 ,主槽摆动频繁 ,大量细颗粒泥沙在由咸淡水交汇形成的河口环流系统中升沉往复 ,构筑了大…