伶仃洋夏季叶绿素a时间变化特征及分析     

曾滇婷  李君益  谢玲玲  叶小敏  周达 《热带海洋学报》2022,41(2):16-25

文章使用2019年7月5日—20日在珠江河口伶仃洋定点连续观测的海表面叶绿素a质量浓度、海表面气温、气压、风速、风向、海表温度、盐度、流速、流向、遥感降雨量数据和中等分辨率成像光谱仪可见光波段影像, 利用小波分析和集成经验模态分解方法分析了观测期间内伶仃洋海表面叶绿素a的时间变化特征及其影响因子。分析结果表明, 观测期间海水表层叶绿素a质量浓度的变化范围为0.44~1.75µg·L^-1, 平均值为0.80µg·L^-1, 其变化周期主要为6h、12h和24h。其与相对应周期的潮流存在明显的相位关系, 并且在降雨后两者的相位关系发生了转换。7月5日—12日, 叶绿素a与潮流基本呈反相位关系, 涨急时叶绿素a质量浓度低, 落急时叶绿素a质量浓度较高, 浓度相差约为0.3µg·L^-1。珠江流域在7月8日—13日发生了一次强降雨过程, 降雨前后海水表层叶绿素a质量浓度在6h、12h和24h周期波段的振幅由0.02~0.09µg·L^-1增加到0.15µg·L^-1左右。同时, 降雨对珠江河口的叶绿素a质量浓度造成了一个持续80h的增加过程, 浓度增加了0.3µg·L^-1。发生降雨后, 7月13日—20日期间潮流滞后于叶绿素a约6h, 水位最高时叶绿素a质量浓度最低, 水位最低时叶绿素a质量浓度最高。由以上结果可以看出, 降雨不仅引起了河口区叶绿素a质量浓度的增加, 还造成了叶绿素a和潮流间相位关系的转换。  相似文献   

基于流变仪测试海底浅表层软黏土不排水强度研究     

缪栋杰  宋丙辉  宋玉鹏  孙永福  苏志明  刘绍文 《海洋工程》2022,40(6):97-104

鉴于海底浅表层软黏土强度测试精细化程度不足的现状,引入流体测试中的流变仪,对青岛海域海底浅表层软黏土开展多组原状和重塑试样的不排水剪切强度试验,通过对比静力触探和微型十字板测试结果,验证了流变仪测试方法的有效性。基于流变仪试验结果,揭示了海底软黏土原状和重塑状态下不排水剪切破坏模式,探讨了海底软黏土不排水剪切强度和灵敏度随埋深及液性指数的发展演变趋势,评价了软黏土的结构性特征。最后,引入含水率与液限之比对海底浅表层软黏土重塑不排水剪切强度进行了归一化分析,为近海海洋开发活动提供技术支撑。  相似文献   

我国大洋钻探船的建造需求和功能设计          下载免费PDF全文

杨磊  秦升杰  景春雷  李宝钢  刘学勤  刘保华 《海洋开发与管理》2019,36(2):68-71,85

为加快我国大洋钻探船的设计和建造,填补国内该领域的空白,保障我国对深海矿产资源的勘探和开发利用,文章概述世界主要大洋钻探船的基本情况,分析我国建造大洋钻探船的必要性和经验基础,并提出我国大洋钻探船的功能设计。研究结果表明:参与国际合作项目的大洋钻探船主要包括美国"格罗玛·挑战者"号、"乔迪斯·决心"号和日本"地球"号;从开发利用深海矿产资源和深度参与国际海底事务的角度,我国对大洋钻探船的需求迫在眉睫,且我国已在深水勘察船和钻井船等的设计和建造方面积累了宝贵经验;我国大洋钻探船的功能设计主要包括船型、总体布置、推进和定位方式、钻探和岩芯采集系统以及船载实验室等方面,应参考其他相关和类似船舶,结合我国深海大洋勘探和开发利用的具体任务需求综合设计。  相似文献   

Sound speed dispersion characteristics of three types of shallow sediments in the southern yellow sea     

Guangming Kan  Baohua Liu  Xiangmei Meng  Guanbao Li  Qingfeng Hua 《Marine Georesources & Geotechnology》2018,36(7):853-860

To accurately characterize sound speed dispersion of shallow sediments in the Southern Yellow Sea, three types of sediments, i.e., silt, clayey silt, and silty clay, were selected to measure the sound speeds at 25–250?kHz. Over the frequency range, the sound speeds vary approximately from 1,536 to 1,565?m?s^?1 in silt sediment, from 1,511 to 1,527?m?s^?1 in clayey silt sediment, and from 1,456 to 1,466?m?s^?1 in silty clay sediment. The sound speed exhibits a slow increase with frequency in a nearly linear gradient, but these three types of sediments have different sound speed dispersion characteristics. The silt sediment with relatively coarse grains has the most significant sound speed dispersion, while the sound speed dispersions of the two others are relatively weak. Comparison between the measured dispersions and the model predictions shows that the grain-shearing model can match the measured data at most of frequencies. Nevertheless, when the grain bulk modulus was assigned 3.2?×?10¹⁰?Pa according to relevant references, the Biot–Stoll model predictions were higher than the measured values at high frequencies; when it was assigned a relatively small value of 2.8?×?10¹⁰?Pa, the model predictions achieved optimal matching with the measured values.  相似文献   

Channel activity of trunk rivers of the Amurskaya region in conditions of current economic management     

《Geography and Natural Resources》2008,29(2):137-141

Based on analyzing the recent research data on the Middle and Upper Amur, it is shown that the flow regulation of the Zeya and asymmetric engineering development of the Amur riversides modify the character, intensity and, in some places, the rearrangement direction of separate channel forms as well as of the channel as a whole. In the Amurskaya region, not only do the technogenic effects on the drainage area manifest themselves in the activity of low-order water streams, but they have influence on the operation of large rivers.  相似文献   

基于Flow-3D的抗拖网海床基冲刷数值模拟          下载免费PDF全文

于凯本  杨涛  高健  林广义  孟庆健  宗乐 《海洋学研究》2017,35(3):91-98

基于Flow-3D软件,建立抗拖网海床基沙土基床冲刷的三维数学模型,控制水流流速和泥沙粒径,对不同条件下抗拖网海床基周围沙土基床的冲刷进行数值模拟,并分析了抗拖网海床基最大冲刷深度随这两种因素改变的趋势。结果表明,抗拖网海床基沙土基床冲刷坑深度随海流流速增大而增加,在设定其他条件不改变的情况下,冲刷坑的加深速度随着流速增大会逐渐减缓,最终达到冲淤平衡。同时,由于海底环境复杂多变,导致模型与实际情况有一定的差异,还需在后续的研究中进一步进行优化。  相似文献   

A Corrected Solid Boundary Treatment Method for Smoothed Particle Hydrodynamics     

CHEN Yun-sai  ZHENG Xing  JIN Shan-qin  DUAN Wen-yang 《海洋工程》2017,31(2):238-247

Smoothed Particle Hydrodynamics method (SPH) has a good adaptability for simulating of free surface flow problems. However, there are some shortcomings of SPH which are still in open discussion. This paper presents a corrected solid boundary handling method for weakly compressible SPH. This improved method is very helpful for numerical stability and pressure distribution. Compared with other solid boundary handling methods, this corrected method is simpler for virtual ghost particle interpolation and the ghost particle evaluation relationship is clearer. Several numerical tests are given, like dam breaking, solitary wave impact and sloshing tank waves. The results show that the corrected solid boundary processing method can recover the spurious oscillations of pressure distribution when simulating the problems with complex geometry boundary.  相似文献   

Insights into ore genesis of the Jinding Zn–Pb deposit,Yunnan Province,China: Evidence from Zn and in-situ S isotopes     

《Ore Geology Reviews》2017

The Jinding Zn–Pb deposit located in the Mesozoic-Cenozoic Lanping Basin of southwest China has ore reserves of ∼ 220 Mt with an average grade of 6.1% Zn and 1.3% Pb. The mineralization is hosted by sandstone in the Early Cretaceous Jingxing Formation and limestone breccia in the Paleocene Yunlong Formation. Mineralization in both types of host rocks is characterized by a paragenetic sequence beginning with marcasite–sphalerite (Stage 1) followed by pyrite–marcasite–sphalerite–galena (Stage 2), and then galena–sphalerite–pyrite–sulfate–carbonate (Stage 3). Pyrite from these stages have different δ³³S compositions with pyrite from Stage 1 averaging − 9.6‰, Stage 2 averaging − 8.9‰, and Stage 3 averaging + 0.3‰. Sphalerite hosted by the sandstone has similar δ⁶⁶Zn values ranging from 0.10 to 0.30‰ in all stages of the mineralization, but sphalerite samples from the limestone breccia-hosted ore show variable δ⁶⁶Zn values between − 0.03 and 0.20‰. Our data on sphalerite precipitated during the earlier stages of mineralization has a constant δ⁶⁶Zn value and cogenetic pyrite displays a very light sulfur isotope signature, which we believe to reflect a sulfur source that formed during bacterial sulfate reduction (BSR). The Stage 3 sphalerite and pyrite precipitated from a late influx of metal-rich basinal brine, which had a relatively constant variable δ⁶⁶Zn isotopic composition due to open system isotope fractionation, and a near zero δ³³S composition due to the influence of abiotic thermochemical sulfate reduction from observed sulfates in the host rock.  相似文献   

Major Miocene geological events in southern Tibet and eastern Asia induced by the subduction of the Ninetyeast Ridge     

Xinlei Sun  Wei-dong Sun  Yong-bin Hu  Wei Ding  Trevor Ireland  Mei-zhen Zhan  Ji-qiang Liu  Ming-xing Ling  Xing Ding  Zhao-feng Zhang  Wei-ming Fan 《中国地球化学学报》2018,37(3):395-401

Cenozoic adakitic rocks in the Gangdese changed from barren continental melts to ore-forming slab melts at ~ 23 Ma. The distribution and chemical characteristics of the ore-forming adakites point to an association with the Ninetyeast Ridge. The subduction of the thick, rigid Ninetyeast Ridge changed the geometry and rheology of the eastern Tibetan Plateau lithosphere and asthenosphere, restrained the eastward escape of asthenospheric mantle as well as continental fragments, and promoted the uplift and building of the Tibetan Plateau, which consequently changed the tectonic and climatic regimes in eastern Asia.  相似文献   

南大西洋14.0°S热液区热液硫化物矿物学特征及地质意义     

李兵  石学法  杨耀民  叶俊  方习生 《矿物学报》2015,(1):35-43

南大西洋14.0°S热液区是由我国在大西洋中脊首次发现的热液区,该热液区位于南大西洋中脊与卡蒂诺(Cardno)转换断层相交的离轴内角位置。本文利用透反显微镜和X射线衍射(XRD)方法,对14.0°S热液区的热液硫化物进行了矿物学研究。结果显示,热液硫化物按照矿石构造可分为块状硫化物和烟囱残片两类,块状硫化物包括富铁和富铜硫化物,烟囱残片为富铁硫化物。块状硫化物矿石根据孔隙发育程度的差异,又可分为致密型和多孔硫化物矿石,这种致密程度的差异取决于硅质物质的含量。块状硫化物矿相学特征表明,本区热液活动至少存在3个期次,表层堆积矿石中硅质物质的大量产出很可能与侵入型网脉矿的发育有关。表层堆积矿石贫Zn的特征,指示虽然该区热液具有多期次性,但热液系统内Zn再活化作用不显著,这种特征很可能是由于本区洋壳较好的渗透性导致。  相似文献