CRS-diagrams for design calculations of the stability of ships

This paper describes the development of a fast diagrammatic method to determine the geometric part of a ship's stability lever, the MS. Additionally, diagrams are given of the contribution to the stability of erections: deck houses and superstructures. The methods are intended for use in the design work.     

中国东部海域中239+240Pu的来源与沉积过程研究

本文对东海及毗邻海域中239+240Pu比活度、240Pu/239Pu原子比值和239+240Pu累积通量或沉积通量数据进行整理,首次从大气沉降、海水中、生物体中、沉积物捕获器中以及沉积物中的239+240Pu 5个方面阐述了东海及毗邻海域中239+240Pu的地球化学行为。研究结果表明,全球大气沉降和太平洋核试验场输入的239+240Pu是东海海水和沉积物中239+240Pu的两个主要来源;在长江径流、浙闽沿岸流、台湾暖流、黑潮与上升流等水团的混合作用以及清除作用的影响下,东海近岸海水中239+240Pu浓度在时间上呈现被清除而减少的趋势,相应近岸浅水区沉积物中239+240Pu的埋藏深度高于远岸深水海域。在黑潮入侵和上升流的作用下,冲绳海槽区尤其是台湾岛东北部,沉积物中的239+240Pu比活度与沉积通量显著增大。同时,利用东海表层沉积物中239+240Pu比活度和240Pu/239Pu原子比值的相关关系证实了台湾东北部黑潮底层分支流的存在,并指示出台湾暖流与黑潮底层分支流可能交汇的海域位置。     

Concepts and science for coastal erosion management - An introduction to the Conscience framework

The main objective of the Conscience project was to develop and test concepts, guidelines and tools for the sustainable management of erosion along the European coastline, based on the best available scientific knowledge and on existing practical experience. Four concepts are potentially capable of providing the nexus between scientific knowledge and management: coastal resilience, coastal sediment cell, favourable sediment status and strategic sediment reservoir. The project has tested the use of these concepts and found that they are useful, provided that they are positioned and linked within a logical structure that we shall call the Conscience “Frame of Reference”, defined in time and space and supported through data and monitoring. Practical experience in six coastal sites in Europe has shown that the use of this Frame of Reference together with these concepts can make management objectives explicit and transparent. It can therefore support the design of an appropriate, resilience based coastal erosion management practice.     

A legal regime for the Arctic?: Interplay with the Law of the Sea Convention

The Law of the Sea Convention constrains regional environmental regimes, especially with respect to navigation beyond the territorial sea. Existing soft-law institutions, notably the Arctic Council, have already strengthened environmental governance in the region by (1) improving the knowledge base; (2) preparing practical guidance on risk reduction; (3) highlighting in broader regulatory fora the Arctic dimension of problems like long-range transported hazardous compounds; and (4) supporting the capacity of Arctic states to implement existing commitments. None of those functions would be much enhanced by a legally binding Arctic environmental regime. The political impediments to reaching circumpolar agreement on a single comprehensive legal regime would suggest a flexible approach to norm building that seeks productive interplay with existing institutions.     

The targets of management rules for marine mammal populations require justification: A reply to

The management of anthropogenic impacts on marine mammal populations involves the setting of targets that are built on assumptions and choices. Scientific methods can be used to investigate the implications of management actions, but the choice of overall objectives and priorities lies outside science. A recent paper (Potential biological removal and other currently used management rules for marine mammal populations: A comparison in Marine Policy), summarised the characteristics of the main approaches currently used to set conservation management targets for marine mammal populations in order to provide a basis for discussion of the targets they contain. Cooke et al. (Management rules for marine mammal populations: A response to Lonergan in Marine Policy) responded, giving some important additional information about these management rules. However most of that paper's criticisms were incorrect or misplaced. Specifically, it erroneously treated an example of how PBR could be reworked, to make its abundance explicit, as a proposal to ignore uncertainty in managing populations. This paper addresses Cooke's main criticisms, and suggests that explicit justifications should be an important part of the process of setting targets for the management of marine mammal populations.     

Large-scale turbulence under a solitary wave: Part 2: Forms and evolution of coherent structures

The instantaneous turbulent velocity field produced by a broken solitary wave propagating on a 1 in 50 plane slope was measured in the longitudinal transverse plane in the middle part of the water column and near the bottom using a stereoscopic particle image velocimetry system. These measurements showed that large-scale turbulence first arrived in the form of a downburst of turbulent fluid. In the middle of the water column, the downbursts arrived shortly after the wave crest had passed. Each downburst was accompanied by two counter-rotating vortices. The latter grew rapidly in size to become a prominent feature of the flow field. Each vortex had a typical length scale of 1/2 to 1 water depth, and carried most of the turbulent kinetic energy in the region between the vortices. Near the bottom, the counter-rotating vortices were not as well defined and covered only a small plane area compared to the entire flow structure. The turbulent fluid descending from above diverged at the bed and the resulting flow structure developed an elongated shape as the source of down-flow travelled onshore with the broken wave. It was found that the transverse spacing between adjacent downbursts ranged from 2 to 5 times the local still water depth. Since vortices cannot end in the interior of the fluid, the counter-rotating vortices must extend to the free surface in the form of a vortex loop. It was suggested that these vortex loops were produced by bending and stretching of primary vorticity generated in the wave breaking process, possibly as a result of three-dimensional water surface deformation. The vortex loops were then carried downward by the falling water from the broken wave.     

Sea Grant in Latin America?: Adapting the US Sea Grant model of linked applied research,extension, and education to a Latin American Context—Is there a fit?

This paper explores the application of the US Sea Grant model of applied research, extension, and education to two case studies in Latin America: Coastal Ecuador and the Gulf of Fonseca. The analysis is based on a series of meetings and roundtables with in-country partners and leaders of the US Sea Grant program. We conclude that the Sea Grant model provides an institutional structure that Latin America lacks and the model's features would improve governance of marine and coastal resources through more effective linkages between coastal communities, universities, and policy/decision makers at local, national, and international levels.     

The role of macrophytes as a refuge and food source for the estuarine isopod Exosphaeroma hylocoetes ( )

The role of submerged macrophytes as refugia from fish predation and as possible food sources for the estuarine isopod Exosphaeroma hylocoetes ( Barnard, K.H., 1940) was investigated. Laboratory experiments tested the effectiveness of artificial vegetation, replicating submerged vegetation, in enabling isopods to elude selected fish predators Rhabdosargus holubi, Glossogobius callidus, Monodactylus falciformis and Clinus cottoides. Isopods preferentially hid in the vegetation (>90%), even in absence of fish. The predatory fish had varying success in finding isopods within the vegetation. Isopod mortality ranged from 2% (R. holubi) to a maximum of 87% (C. cottoides) within vegetation, depending on the fish predator present. Stable isotope and fatty acid analyses ruled out the submerged macrophyte Ruppia maritima and inundated fringing grasses as direct food sources, but highlighted the epiphytic biota (mainly diatoms) found on the submerged vegetation and sediments as more likely food sources. These findings are consistent with gut content analyses. The results suggest that the close association of E. hylocoetes with R. maritima is the result of the vegetation providing the isopod with a refuge against fish predation as well as areas of increased food availability.     

The form of the asymptotic depth-limited wind-wave spectrum: Part III — Directional spreading

The directional spreading of both the wavenumber and frequency spectra of finite-depth wind generated waves at the asymptotic depth limit are examined. The analysis uses the Wavelet Directional Method, removing the need to assume a form for the dispersion relationship. The paper shows that both the wavenumber and frequency forms are narrowest at the spectral peak and broaden at wavenumbers (frequencies) both above and below the peak. The directional spreading of the wavenumber spectrum is bi-modal above the spectral peak. In contrast, the frequency spectrum is uni-modal. This difference is shown to be the result of energy in the wind direction being displaced from the linear dispersion shell. A full parametric relationship for the directional spreading of the wavenumber spectrum is developed. The analysis clearly shows that typical dispersion relationships are questionable at high frequencies and that such effects can be significant. This result supports greater attention being focussed on the routine recording of wavenumber spectra, rather than frequency spectra.     

海洋中90Sr:日本周边海域与南海的对比

90Sr长期被视为最重要的人工放射性核素之一,日本福岛核事故导致包括90Sr在内的大量放射性物质泄漏进入海洋,厂区储水罐中冷却废水至今仍然存在大量90Sr。海洋中90Sr分析方法却繁琐耗时,导致核事故后的90Sr研究较为匮乏,且缺乏系统的认识。本研究在2015?2018年期间测量南海海水和多种海洋生物(马尾藻、海虾、牡蛎、红树林植物、造礁珊瑚)中90Sr的基础上,深入分析核事故后日本周边海域和南海90Sr的比活度水平与环境半衰期。结合文献资料,本研究发现1975?2010年期间日本近岸海水90Sr的环境半衰期为15.4 a,2011年的核事故后日本周边海洋中90Sr比活度显著升高,基于ERICA软件定量计算核事故后90Sr对海洋鱼类的剂量率比核事故前的结果高5个数量级。南海作为福岛核事故后北太平洋环流的下游海域,本文进一步构建1984?2018年期间南海90Sr比活度的历史曲线,发现核事故前后南海90Sr比活度水平没有可识别的变化,进一步定量计算南海90Sr的环境半衰期为26.7 a,发现边缘海和大洋中90Sr和137Cs环境半衰期格局差异与核素(90Sr和137Cs)的源汇过程(河流输入和海洋生物泵)密切相关。鉴于海洋中90Sr分析方法的挑战性,本文发现在10多种海洋生物中造礁珊瑚骨骼几乎拥有最高的90Sr浓集因子(约1 000 L/kg),同时具有较易大量获取、固定附着生长、连续高分辨率记录、前处理简单快速等优点,很可能是海洋中90Sr可靠的指示生物。造礁珊瑚中90Sr研究将有利于揭示人工放射性核素的源汇过程,同时为我国海洋放射性监测方案和相关标准导则的优化和完善提供有益的参考。