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61.
潮沟是潮滩的主要地貌类型之一,潮沟信息的检测对湿地生态环境的监测和保护有着重要意义。本文以长江口九段沙下沙北部发育比较复杂的潮沟为研究对象,使用2016年1月26日Landsat8全色波段数据,采用了一种融合小波变换、最大类间方差法和数学形态学的方法对潮沟边缘信息进行了检测。小波变换中通过减小高层小波系数,达到弱化潮滩灰度变化的目的;通过增大低层小波系数,达到增强潮沟信息的目的;利用数学形态学和图像之间的几何(加减乘)运算,完成潮沟的提取;最后,分别在原始数据和检测结果相应的位置取样进行精度验证,样方潮沟面积一致性精度平均为92.1%。 相似文献
62.
Yanhui Suo Sanzhong Li Xiyao Li Zhen Zhang Dong Ding 《Marine Geophysical Researches》2017,38(1-2):61-70
Deep-sea hydrothermal vents possess complex ecosystems and abundant metallic mineral deposits valuable to human being. On-axial vents along tectonic plate boundaries have achieved prominent results and obtained huge resources, while nearly 90% of the global mid-ocean ridge and the majority of the off-axial vents buried by thick oceanic sediments within plates remain as relatively undiscovered domains. Based on previous detailed investigations, hydrothermal vents have been mapped along five sections along the Southwest Indian Ridge (SWIR) with different bathymetry, spreading rates, and gravity features, two at the western end (10°–16°E Section B and 16°–25°E Section C) and three at the eastern end (49°–52°E Section D, 52°–61°E Section E and 61°–70°E Section F). Hydrothermal vents along the Sections B, C, E and F with thin oceanic crust are hosted by ultramafic rocks under tectonic-controlled magmatic-starved settings, and hydrothermal vents along the Section D are associated with exceed magmatism. Limited coverage of investigations is provided along the 35°–47°E SWIR (between Marion and Indomed fracture zones) and a lot of research has been done around the Bouvet Island, while no hydrothermal vents has been reported. Analyzing bathymetry, gravity and geochemical data, magmatism settings are favourable for the occurrence of hydrothermal systems along these two sections. An off-axial hydrothermal system in the southern flank of the SWIR that exhibits ultra-thin oceanic crust associated with an oceanic continental transition is postulated to exist along the 100-Ma slow-spreading isochron in the Enderby Basin. A discrete, denser enriched or less depleted mantle beneath the Antarctic Plate is an alternative explanation for the large scale thin oceanic crust concentrated on the southern flank of the SWIR. 相似文献
63.
Zhiteng?YuEmail author Jiabiao?LiEmail author Weiwei?Ding Jie?Zhang Aiguo?Ruan Xiongwei?Niu 《Marine Geophysical Researches》2017,38(1-2):85-104
The Southwest Subbasin (SWSB) is an abyssal subbasin in the South China Sea (SCS), with many debates on its neotectonic process and crustal structure. Using two-dimensional seismic tomography in the SWSB, we derived a detailed P-wave velocity model of the basin area and the northern margin. The entire profile is approximately 311-km-long and consists of twelve oceanic bottom seismometers (OBSs). The average thickness of the crust beneath the basin is 5.3 km, and the Moho interface is relatively flat (10–12 km). No high velocity bodies are observed, and only two thin high-velocity structures (~7.3 km/s) in the layer 3 are identified beneath the northern continent-ocean transition (COT) and the extinct spreading center. By analyzing the P-wave velocity model, we believe that the crust of the basin is a typical oceanic crust. Combined with the high resolution multi-channel seismic profile (MCS), we conclude that the profile shows asymmetric structural characteristics in the basin area. The continental margin also shows asymmetric crust between the north and south sides, which may be related to the large scale detachment fault that has developed in the southern margin. The magma supply decreased as the expansion of the SWSB from the east to the west. 相似文献
64.
本实验以坛紫菜自由丝状体为材料,研究不同培养方式(静置、摇床、通气)和换水频率(5d、7d、10d、20d)对丝状体生长及藻胆蛋白(PE、PC)含量变化的影响。研究结果表明:坛紫菜自由丝状体在摇床培养条件下生长较好,特定生长速率可达10.832 7%~10.891 5%;摇床培养下的丝状体PE含量相对静置培养的较高一些,通气培养的相对较低,最高为36.816 8mg/g;静置条件下培养的丝状体PC含量最高,摇床培养次之,通气培养最低,最低为1.082 4mg/g。相同培养方式下,换水频率对丝状体特定生长速率影响不大;除通气培养外,换水频率20d其PE、PC含量较高。方差分析结果表明:实验范围内的培养方式及换水频率对丝状体特定生长速率大小、PE和PC含量不存在交互作用。本文实验结果对坛紫菜自由丝状体产业化应用于食品加工、色素提取等产业提供了实验理论和依据。 相似文献
65.
66.
热带西太平洋海洋上层热含量的分布特征及其年际变化的分析 总被引:1,自引:0,他引:1
选用海面至20℃等温线所处深度水层的平均温度来表征研究海域海洋上层热含量。利用这一特征值,分析1986—1990年期间热带西太平洋边缘海域海洋上层热含量在秋季的分布特征和年际变化。结果表明:(1)热含量呈南高北低分布,在7.5-22.1°N范围内。以130°E断面为代表,热含量的平均递减率为0.179(℃/纬度);(2)热含量的分布主要取决于环流系统,其等值线因受黑潮和棉兰老海流的影响而由纬向分布转向经向分布。某些区域因受暖涡及冷涡的影响而呈封闭状分布;(3)热含量的年际变化与E1Nino事件存在着很好的相关性,在E1Nino事件发生期间,热含量变得很低,高热含量(大于26.5℃)海区的分布范围明显缩小。 相似文献
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69.
Liuyang Li Chao Wu Jun Sun Shuqun Song Changling Ding Danyue Huang Laxman Pujari 《海洋学报(英文版)》2020,39(12):30-41
N2 fixation rates(NFR, in terms of N) in the northern South China Sea(nSCS) and the East China Sea(ECS) were measured using the acetylene reduction assay in summer and winter, 2009. NFR of the surface water ranged from 1.14 nmol/(L·d) to 10.40 nmol/(L·d)(average at(4.89±3.46) nmol/(L·d), n=11) in summer and 0.74 nmol/(L·d) to 29.45 nmol/(L·d)(average at(7.81±8.50) nmol/(L·d), n=15) in winter. Significant spatio-temporal heterogeneity emerged in our study: the anticyclonic eddies(AE)(P... 相似文献
70.
Zhi Ding Fenzhen Su Yanan Chen Ying Liu Xue Feng Wenqiu Hu Fengqin Yan He Li Pujia Yu Xuguang Tang 《海洋学报(英文版)》2023,42(2):163-174
Increasing intense human activities have largely changed the coastal landscape and caused many environmental issues. However, whether human-induced activities could change the coastal land use gradient pattern, an important coastal zonal characteristic along the sea–land direction, remains unclear. Manila Bay was selected as the study area in this work. According to the distance of the land use and land cover(LULC) to the coastline, we clustered the typical coastal land use sequence patterns(CLU... 相似文献