东山湾贝类养殖容量的估算

以初级生产力为基础，应用营养动态模式和沿岸海域能流分析模型，估算东山湾贝类年生产量分别为269331t和295767t，平均282549t。扣除潮间带、潮下带和吊养区浮筏、随着基及延绳上附着的非养殖滤食性附着动物自然现存量35760t，贝类可养殖量为246789t。应用统计分析和逻辑斯谛种群增长模型估计贝类可养面积为11839hm^2，其中缢蛏635hm^2，石蛎1160hm^2,吊蛎1525hm^2，翡翠贻贝633hm^2，菲律宾蛤仔1154hm^2，扇贝698hm^2，江瑶248hm^2，泥蚶601hm^2，巴非蛤4151hm^2，凸壳肌蛤1034hm^2。1998年实际养殖面积和养殖产量分别为10581hm^2和220564t。尚有1258hm^2,26225t的扩大开发潜力。文中还讨论了合理布局和优化养殖结构问题。     

Estimation of Uplift Capacity of Rapidly Loaded Plate Anchors in Soft Clay

Plate anchors are extensively used in civil engineering constructions as they provide an economical alternative to gravity and other embedded anchors. The rate of loading is one of the important factors that affects the magnitude of soil resistance as well as soil suction force. This article outlines the effect of pullout rate on uplift behavior of plate anchors (70 mm diameter) buried in soft saturated clay by varying the pullout rate from 1.4 mm/min to 21.0 mm/min. The variation of breakout force and suction force with embedment depth and rate of pull are presented. A correlation between the rate of increase of undrained strength of clay and anchor capacity with rate of strain has been established. Finally an empirical equation has been proposed that includes the rate of pull in the estimation of breakout capacity of anchors.     

Discussion: A review on the behaviour of helical piles as a potential offshore foundation system

Abstract

Helical piles have emerged as an attractive foundation system for offshore applications with renewed interest from the offshore community. Significant research gap currently exists in transferring this technology offshore and this paper discusses how existing and emerging knowledge can be successfully used to bridge some of the gaps. We focus on the Coupled Eulerian Lagrangian (CEL) large deformation finite element (LDFE) modelling technique that is commercially available and can be used to model the three-dimensional installation process with consideration of strain rate and softening effects in soft offshore clays. A helical pile of L?=?7.5?m long is modelled with one or two large-diameter helices (D?=?2?m) attached to a central shaft of d?=?0.5?m in diameter.The net effect of strain rate and softening is to increase the installation torque. The measured torque is within the range of 200–400?kN.m for the offshore clay and the pile geometry studied. Additional helices increase the uplift force but to a lesser degree than that of the measured torque. Remoulding induced strength reduction is found to be within the range of 25–33% of the intact clay strength. Issues of extracting and reusing offshore helical pile foundations are discussed.     

Sustainable shellfish aquaculture in Saldanha Bay,South Africa

The carrying capacity for bivalve shellfish culture in Saldanha Bay, South Africa, was analysed through the application of the well-tested EcoWin ecological model, in order to simulate key ecosystem variables. The model was set up using: (i) oceanographic and water-quality data collected from Saldanha Bay, and (ii) culture-practice information provided by local shellfish farmers. EcoWin successfully reproduced key ecological processes, simulating an annual mean phytoplankton biomass of 7.5 µg Chl a l^–1 and an annual harvested shellfish biomass of about 3 000 tonnes (t) y^–1, in good agreement with reported yield. The maximum annual carrying capacity of Small Bay was estimated as 20 000 t live weight (LW) of oysters Crassostrea gigas, or alternatively 5 100 t LW of mussels Mytilus galloprovincialis, and for Big Bay as 100 000 t LW of oysters. Two production scenarios were investigated for Small Bay: a production of 4 000 t LW y^–1 of mussels, and the most profitable scenario for oysters of 19 700 t LW y^–1. The main conclusions of this work are: (i) in 2015–2016, both Small Bay and Big Bay were below their maximum production capacity; (ii) the current production of shellfish potentially removes 85% of the human nitrogen inputs; (iii) a maximum-production scenario in both Big Bay and Small Bay would result in phytoplankton depletion in the farmed area; (iv) increasing the production intensity in Big Bay would probably impact the existing cultures in Small Bay; and (v) the production in Small Bay could be increased, resulting in higher income for farmers.     

南黄海及相邻陆区松散沉积层磁性地层的研究

本文通过研究区5个钻孔松散沉积岩心磁性地层的划分对比,获知布容与松山极性带的界线,南黄海和陆区北部位于80.0—99.5m。陆区的南部此界线于270.4m深处。松山和高斯极性带的界线,海区未揭露到,其沉积起始时间都小于1.7Ma。而陆区的南、北部分别位于117m和328.2m。高斯和吉尔伯特极性带的界线,陆区北部为140m,而南部区为460.15m。沉积起始时间为3.4Ma。吉尔伯特底界仅北部陆区所揭示,为190.5m。松散沉积层与下伏白垩纪(?)石灰岩接触面位于400.35m,沉积起始时间约17.0Ma。     

三角褐指藻体分泌物质对汞的络合作用

本文测定了一次培养实验和连续培养实验中三角褐指藻胞外产物的变化及其与汞的络合性能。28天的培养过程中测得胞外产物与汞的络合容量C_L为2.6×10~(-5)mol/dm~3;表观稳定常数K′为6.1×10~(10)。该结果解释了细胞培养过程中胞外有机物的释放对汞的解毒机理及对介质中汞形态的转化。     

清淤输泥的新方法新设备

为解决中低滩涂沉积的深厚软粘土层的输送难题,提出了一种清淤输泥的新方法,研制了能远距离输送高浓度、大粘度、低含水量的淤泥和软粘土的土方施工新设备:包括进料口、推送器、表面膜发生器、脉冲切割器、定位系统、智能控制系统、输料管道、管道浮子等。该设备具有能耗低,工效高,效益好;结构简单,故障少,运行维护方便;定位准确性高;自动化程度高等特点。可广泛应用于水利、环保、建筑工程中的淤泥和软粘土输送。     

Prediction of Load Carrying Capacity of Corroded Reinforced Concrete Beam

A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were condueted. The flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic intbrmation of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory resuits are achieved.     

半封闭海湾潮间带部分围垦后纳潮量计算的商榷——以胶州湾为例

传统的海湾(泻湖)纳潮量计算方法不能精确地反映潮间带被部分围垦后纳潮量的实际情况,本考虑围堤的影响,将纳潮量分解为堤基以下的“梯形”区和堤基以上的“矩形”区两部分之和,在理论上更加严密。根据改进后方法算出的胶州湾近期纳潮量比传统方法算出的纳潮量大15％左右。可见,半个多世纪以来胶州湾的纳潮量只减少了约15％．而不是传统方法得出的约25％。     

极谱法测定海水介质的铜络合容量

采用新极谱技术(1.5次微分)的阳极溶出伏安滴定方法测定天然海水的铜络合容量和条件稳定常数。对测试条件、EDTA回收率和有关问题进行了探讨。青岛近岸水样的九次平行测定表明,铜的表现络合容量为3.01×10~(-7)mol/dm~3,条件稳定常数为7.34×10~7,相对标准偏差分别为9.2％和13.8％。