Apparent phytoplankton bloom due to island mass effect

A continuous monitoring of temperature and chlorophyll-a (Chl-a) concentration from a surface water monitoring system and a towed free fall instrument (MVP) around a small island in the Kuroshio showed low sea surface temperature (SST) and high surface Chl-a concentration (SCC) distribution in the lee of the island that indicates typical “island mass effect” phenomena. When the observed Chl-a profiles (0 to 250 m) were integrated, the total amounts in the lee side data were slightly smaller than those of the upstream side of the island. The difference was statistically significant at the 95% confidence level. The cross section diagram of Chl-a indicated the diffusion of subsurface Chl-a maximum (SCM) from the upstream to the downstream flanks of the island. The diffusivity of SCM and the change of potential energy require the same level of strong turbulent dissipation rate at the flanks of the island. That is consistent with our previous direct measurement in a similar hydrodynamic condition. Therefore, the observed high SCC is due to turbulent diffusion of SCM, and clearly showed that high SCC does not require any new production. Although a high fluorescence field behind an isolated island in a strong flow is often visible from satellite images, the images do not necessarily indicate an enhanced primary production at that moment.     

Turbulence in coastal fronts near the mouths of Block Island and Long Island Sounds

Measurements of turbulence were performed in four frontal locations near the mouths of Block Island Sound (BIS) and Long Island Sound (LIS). These measurements extend from the offshore front associated with BIS and Mid-Atlantic Bight Shelf water, to the onshore fronts near the Montauk Point (MK) headland, and the Connecticut River plume front. The latter feature is closely associated with the major fresh water input to LIS. Turbulent kinetic energy (TKE) dissipation rate, ε, was obtained using shear probes mounted on an autonomous underwater vehicle. Offshore, the BIS estuarine outflow front showed, during spring season and ebb tide, maximum TKE dissipation rate, ε, estimates of order 10^− 5 W/kg, with background values of order 10^− 6 to 10^− 9 W/kg. Edwards et al. [Edwards, C.A., Fake, T.A., and Bogden, P.S., 2004a. Spring–summer frontogenesis at the mouth of Block Island Sound: 1. A numerical investigation into tidal and buoyancy-forced motion. Journal of Geophysical Research 109 (C12021), doi:10.1029/2003JC002132.] model this front as the boundary of a tidally driven, baroclinically adjusted BIS flow around the MK headland eddy. At the entrance to BIS, near MK, two additional fronts are observed, one of which was over sand waves. For the headland site front east of MK, without sand waves, during ebb tide, ε estimates of 10^− 5 to 10^− 6 W/kg were observed. The model shows that this front is at the northern end of an anti-cyclonic headland eddy, and within a region of strong tidal mixing. For the headland site front further northeast over sand waves, maximum ε estimates were of order 10^− 4 W/kg within a background of order 10^− 7–10^− 6 W/kg. From the model, this front is at the northeastern edge of the anti-cyclonic headland eddy and within the tidal mixing zone. For the Connecticut River plume front, a surface trapped plume, during ebb tide, maximum ε estimates of 10^− 5 W/kg were obtained, within a background of 10^− 6 to 10^− 8 W/kg. Of all four fronts, the river plume front has the largest finescale mean-square shear, S² ~ 0.15 s^− 2. All of the frontal locations had local values of the buoyancy Reynolds number indicating strong isotropic turbulence at the dissipation scales. Local values of the Froude number indicated shear instability in all of the fronts.     

Designing a Network of Coral Reef Marine Protected Areas in Hainan Island,South China

Overexploitation of reef resources and increasing coastal tourism have severely damaged the health of coral reef ecosystems around Hainan Island, South China. Only some reef sites are protected, and the effectiveness of the marine protected areas (MPA) appears inadequate. Networks of MPAs have been widely proposed as a more effective tool for reef conservation. However, little is known about the overall state of the island's coral reefs, and no guidelines exist for MPA network building in China. In this study, the information currently available on the distribution and condition of Hainan's coral reefs is comprehensively used to assess reef status, and to identify other reef areas prior to protection. An MPA network around the island is proposed in terms of monitoring, legal, and management aspects to improve the conservation effectiveness. This could also serve as a model for developing MPA networks for other coastal areas with respect to coral reef conservation.     

大平岛围垦工程对航道、码头影响研究

基于工程海域条件分析,建立了平面二维潮流泥沙数学模型。在实测资料验证良好的基础上,对大平岛围垦工程前、后的潮流、悬沙场等进行了模拟,就工程对围区附近航道、码头的影响进行了分析研究。研究表明,本工程的实施对周边海域没有大范围的根本性影响,其影响主要集中在西侧水道的局部水域,会使处于围区西侧水道的燕山热电厂煤码头及其航道等产生淤积,建议定期疏浚或采取其它工程措施。     

洋口人工岛工程的合龙设计与实施

洋口人工岛是南通洋口港区陆岛跨海通道的终点、现代物流仓储的基地和液化天然气接收站的承载平台。文章以洋口人工岛工程为例,以水力计算为理论依据,从龙口的合龙时机、龙口位置和宽度确定、龙口防护、堵口方法和顺序以及龙口合龙过程中需注意的要点几个方面对龙口的合龙进行了分析和探讨。     

交通运输部东海救助局湄洲救助基地码头工程选址方案研究

湄州救助基地拟建在台湾海峡西侧的湄洲岛.该岛潮流、波浪多变且地形、地质条件复杂.为确保救助船出勤与执行任务的安全、可靠,综合考虑了设计初拟的两处港址泥沙、波浪及骤淤和掩护条件等情况,进行了比较和论证分析,最后得出选址结论.     

册子岛油库码头及航道回淤研究

根据册子岛油库及30万吨级原油码头投产5年多的自然条件、水深测图资料和历次疏浚资料,分析运营以来册子岛码头前沿港池和航道的淤积变化趋势,并就其产生的原因进行了深入探讨,在此基础上提出了册子岛原油码头前沿港湾及航道的维护疏浚建议。研究成果对于册子岛30万吨级原油码头的船舶安全进出港口和其它大型码头深水航道的建设及发展具有一定的参考价值。     

大、小门岛连岛工程对周围海区环境影响研究

基于TK-2D软件,采用潮流泥沙数值模拟手段对大门岛与小门岛连岛工程对周围海区环境的影响进行了研究和论证。研究结果表明,大门岛与小门岛连岛工程对周围海区环境影响很小,有利于出海航道(中水道和黄大岙水道)、沙头水道和小门水道水深维护,对黄大峡水道水深影响亦很小。因此,大门岛与小门岛连岛工程是可行的。