杭州湾北岸潮滩沉积物粒度的时间变化及其沉积动力学意义

2002年5月-2003年4月对杭州湾北岸中潮滩一个固定观测点表层沉积物进行逐日取样,采用库尔特LS100Q型激光粒度仪进行粒度分析,探讨潮滩沉积物粒度随时间的演变。结果表明,潮滩粒度特征在时间上有明显的变化,1～6月潮滩堆积期间沉积物粒度较细,7-12月潮滩侵蚀期间沉积物较粗,其中1月和7月为潮滩冲淤转换期间沉积物粒度显示双峰分布;沉积物午平均粒度亦显示双峰分布,细颗粒部分主要是由于悬沙落淤形成,而粗颗粒部分主要是由于潮滩下部粉、细砂物质向上推移形成。通过潮滩沉积动力学的探讨阐明了潮滩沉积物粒度演变的原因和特点。     

海岸地貌建模方法研究--以长江口九段沙、芦潮港附近边滩为例

河口、海岸是陆海相互作用及人类活动最频繁的地区之一,了解和把握海岸地貌的变迁及发育模式对于海岸资源的开发和保护至关重要。模型是对客观事物的概括和抽象,本文对海岸滩地和水下三角洲地形演变的研究总结了4种方法,重点讨论了模型的构建,并根据作者的研究实例给出了模型的具体应用。在剖面模型的应用中通过不同年代剖面的对比分析可了解海岸地貌的动态变化,平面模型则通过等深线的退缩、扩张及形态变化来研究岸滩的动态冲淤及海岸地形的宏观变化,而冲淤速率分布平面图是分析大范围海域冲淤趋势和局部变化的有效手段。测点统计模型是一种静态分析方法,用来建立测量点的高程和坡度与岸滩冲淤的关系。     

长江口南港航道沙波群研究

本文利用Innerspace449热敏式双频测深仪和GPS(全球定位系统)在长江口南港和南北槽主航道走航观测结果,确认南港(吴淞口以下)上段航道在洪季正常风况下存在尺度较大的沙波群,并对沙波的几何特征、形成条件、迁移速率以及台风后的变化做了初步分析.结果表明:(1)在统计的652个沙波中,平均和最大波长分别为21m和105m.平均和最大波高分别为0.8m和2.7m,波高和波长间具有明显的正相关关系;沙波中72%为单一沙波,复合沙波的波长和沙波指数较大;单一沙波最大、最小和平均沙波指数分别为36.5、11.2和21.8(复合沙波最大可达69.3);随着沙波度的增大,沙波指数呈增大趋势;绝大多数沙波(波高＜1m)是对称或近于对称的,但波高＞1m的沙波通常向海倾斜.(2)沙波沉积物为分选好的细沙,Φ50为2.70.(3)沙波现场水流费劳德数Fr小于0.2,与某些理论相符而与某些水槽实验结果相冲突.(4)大潮和寻常潮一个涨(落)潮过程沙波来回迁移的距离约为1～5m;小潮期间沙波的迁移距离接近0;落潮迁移距离总是大于涨潮.(5)台风后沙波有被掩埋的迹象.结果包括:①沙质床底是形成沙波的重要基础.南北槽虽具有沙波形成的动力条件,但因最大浑浊带发育而造成淤泥质床底,故沙波不发育.②潮汐河口双向流环境下沙波的对称性较好,频繁的水动力变化使沙波的消长和迁移过程更加复杂,但沙波的基本特征和形成条件与单向流河流环境相似.     

丹棱-思濛扇积物中的漫洪相粘土层

在简述丹棱-思氵蒙冲积扇上覆粘土层的分布与特征之后,应用粒度分析方法和孢粉组合来论述其沉积环境,并尝试应用粘土矿物与土体中易累积的稳定化合物含量与淋溶系数(ba)等所代表的粘土风化程度来论证该粘土层的相对年代。     

南极夏季南设德兰群岛东部海域南极大磷虾的摄食策略

Euphausia superba is a key species in the Southern Ocean that serves as a link between primary production and higher trophic levels. To investigate the feeding strategies of E. superba from the eastern South Shetland Islands,fatty acid biomarkers, stable isotope signatures, and an incubation experiment were conducted. The results of the incubation experiment proved that adult E. superba mainly fed on 2–20 μm particles, demonstrating the importance of nanoplankton in their diet. Moreover, significant positive relationships between δ15 N and body size demonstrated that size-related dietary shifts were present in E. superba. Evidence from principal component analysis and the C16:1ω7/C18:4ω3 ratio showed that juveniles preferentially fed on dinoflagellates and adults were more likely to feed on diatoms. Fatty acid profiles in adult E. superba roughly mirrored the different trophic conditions and feeding strategies between stations. Adult E. superba at Stas D2-07, D5-07, DA-01 and DA-02 exhibited elevated levels of C16:1ω7, C18:4ω3, C18:1ω9 and C18:1ω9/C18:1ω7, indicating higher levels of feeding on both phytoplankton and higher trophic diets. In contrast, adult E. superba at Stas D1-03 and D1-04 were characterized by high levels of polyunsaturated fatty acids/saturated fatty acids ratios and low levels of C16:1ω7,C18:1ω7, C18:4ω3, C18:1ω9 and total fatty acids. We inferred that adult krill at Stas D1-03 and D1-04 still suffered from difficult dietary conditions after overwintering. The different dietary conditions between stations suggest a highly plastic feeding strategy of E. superba in the eastern South Shetland Islands.     

Changes in the population structure of Calanus sinicus during summer–autumn in the southern Yellow Sea

Calanus sinicus is a calanoid copepod widely distributed in coastal waters of China and Japan, and oversummering strategies may have major impacts on their population dynamics which in turn affect local marine food web structure. The abundance, stage composition, and sex composition of the planktonic copepod C. sinicus were studied from August to October 2002 in the southern Yellow Sea to understand how its population recovers from the over-summering state. Results showed that C. sinicus had low reproduction in August due to high temperature, except in waters near the Cheju Island with rich food and moderate bottom temperature, but the reproduction rates here decreased in September–October as food availability declined. When temperature dropped in September–October, C. sinicus actively propagated in coastal shallow waters. However, reproduction rates of C. sinicus individuals inhabiting the Yellow Sea Cold Water Mass(YSCWM) remained low during the three months of the study. The percentage of C. sinicus females was high during the reproductive period, which suggests that the sex composition of adult C. sinicus may reflect whether or not the population is in the reproductive mode.Numerous fifth copepodite stage(CV) C. sinicus aggregated in the YSCWM in a suspended developmental stage during the three months of this study, and they potentially served as the parental individuals for population development when conditions became optimal for reproduction later in the year.     

堤线调整对九溪涌潮景观影响评价研究

因建设需要,拟对钱塘江九溪岸段堤线进行调整。九溪岸段是钱塘江知名的观潮点之一,涌潮是该河段一个重要的自然景观资源。为减小堤线调整对涌潮景观的影响,建立了基于有限元/有限体积法的SCHISM三维涌潮模型,复演了九溪涌潮现象,提出了观潮区的涌潮高度、涌高明显的岸线长度和涌高明显的区域面积等三个综合评价指标,对堤线调整给涌潮带来的影响做出了评价。该研究对其他工程对钱塘江涌潮景观的影响评价具有借鉴意义。     

水下激光扫描成像系统及其在冷泉研究中的应用

利用深潜器及其搭载光学设备获得重点调查区的高分辨率影像资料是深远海调查的重要内容,对于研究冷泉、热液等特殊海底环境及其生态系统的组成、空间规模、分布特征以及演化规律具有重要意义。主要介绍了搭载于"发现"ROV的4 500m级L1000型图像和激光扫描系统及其应用实例。利用该系统拍摄并带有位置信息的海底高清照片,首次获得了台西南冷泉区的高清全幅海底拼接图像,并根据该拼接图像对台西南冷泉区的海底特征、空间分布规律和规模进行了直观分析和量化研究,有效地提高了我国深远海近海底测绘的能力。     

三维油气管道初选定线系统设计与实现

针对设计人员在油气管道初选定线时对三维信息的关注及二维油气管道初选定线方案在此方面的不足,基于GoogleEarthComAPI和KML语言,提出了在GoogleEarth上分割加载高分辨率影像数据的方法,及基于KML语言扩展管道要素属性描述的方案,最后以某石油勘察设计单位油气管道初选定线系统为例进行了开发实现。     

青藏高原植被变化对区域气候影响研究进展

陆地生态系统与气候变化之间存在这密不可分的相互作用过程。青藏高原地区是全球气候变化的敏感区,全球变暖对高原陆地生态系统演变的影响非常明显,这必将导致高原生态系统变化。生态系统的变化又将会引起局地、区域气候的响应,导致局地、区域、甚至全球的气候变化。因此研究青藏高原地区植被演变及其与气候变化的关系是一个有着重要学术价值和实际意义的课题。本文在对青藏高原植被与气候关系研究回顾的基础上,介绍了近年来关于青藏高原植被变化对区域气候影响取得的新的进展,提出了一些可能的物理过程,同时指出了研究中存在问题及今后的工作重点。