福建3个港湾和闽南—台湾浅滩海域光学参数的研究

本文根据现场浮游植物光合作用速率和叶缘素a 的测定值,以及海水光强度的衰减变化,计算了海水消光系数,推导了福建东山湾、罗源湾、厦门西港和闽南-台湾浅滩海域海水消光系数与透明度的经验关系式;讨论了悬浮颗粒对不同深度下浮游植物生长速率的影响。结果表明,福建近岸海域光学参数的差异主要在于悬浮物质的贡献;不同季节,生物活动对光学参数也有所影响。最大光合作用速率一般出现在光衰减为10%～30%,频率分布因子为70%～80%。     

Rare earth elements and Opal/CaCO<Subscript>3</Subscript> ratio of sinking particles observed with a time-series sediment trap at the mouth of Tokyo Bay

A time-series sediment trap was deployed from December 1994 to February 2002 at the mouth of Tokyo Bay (35°03′ N, 139°40′ E; water depth, 850 m). Sinking particles were obtained with a time interval of one week at a depth of approximately 100 m above the sea floor. Observed total mass fluxes varied from 3.3 to 226.7 g/m²/day with an average of 28.0 g/m²/day. Concentrations of rare earth elements, Al, Ca and Si in particulate materials were measured. The combustible fraction at 450°C is assumed to be equivalent to the organic matter content. Contents of biogenic materials, namely organic matter, opal and calcium carbonate, were about 30% and the content of lithogenic material was about 70%. Using La/Yb ratios of particles from the sediment trap and Tama-gawa River and surface sediment of Tokyo Bay, it was estimated that about 50% of the lithogenic particles collected in the sediment trap at the mouth of Tokyo Bay originated from resuspended surface sediment in Tokyo Bay. An increasing trend of Opal/CaCO₃ ratio in the sinking particles was found in the spring season. It is suggested that the relative increase of diatoms is due to the decreasing dissolved inorganic nitrogen input into Tokyo Bay.     

Effects of periodic saturation on K0 for a sandstone-mudstone particle mixture

Abstract

Sandstone-mudstone particle mixture (SMPM) is one of the main materials, which has been widely used for filling in and around reservoirs for water conservation projects. During the periodic rising and falling of the water level, the fill material for the embankments, dam, and other waterfront features will also undergo drainage-saturation cycles. The deformation and coefficient of lateral pressure at rest K₀ may be affected by periodic saturation. In this study, a device is modified for testing the K₀ for gravel-soil under periodic saturation. In order to investigate the effects of periodic saturation on K₀, a series of experiments were performed for SMPM under different vertical stress and saturation cycling. K₀^N values of SMPM containing 20% mudstone particles under periodic saturation were obtained. The results shows that the K₀^N initially increased, but eventually reached a stable value with the increasing number of periodic saturation cycles. The magnitude of the coefficient increment was also found to be related to the stress condition. K₀^N is a logarithmic function of the saturation cycling time. By calculating K₀^N with the proposed empirical formula, the deformation and stress distribution of the SMPM filler in waterfront engineering works can be calculated with greater precision.     

钱塘江河口细颗粒泥沙絮凝沉降特性研究

钱塘江口河口上游河流和海域来沙多为细颗粒泥沙,粘性细颗粒泥沙由于其特殊的表面电化学性质遇到强电解质海水而产生絮凝沉降,是形成河口淤积的原因之一。影响絮凝的因素很多,除了电解质,还有泥沙粒径的大小、盐度、含沙量、PH值、温度、有机质含量、矿物成分、水流速度及紊动情况等。本文通过粒度分析、静水沉降、动水沉降等各种实验手段分析钱塘江口泥沙的基本特性,找出最佳絮凝盐度以及泥沙不淤流速等值,初步探讨了细颗粒泥沙的絮凝机理,为治理钱塘江口提供科学依据。     

Investigation on Settling Characteristics of Floes in the Changjiang Estuary, China

- Settling characteristics of floes, including relative settling velocity, relative flocculation coefficient and flocculation exponent, are obtained by the suspended load equations for different size fractions. Data of the Changjiang Estuary suggest that level of flocculation changes from river section, river mouth (turbidity maximum) to offshore area in sequence of low, very high and high. The settling characteristics of floes reflected by in situ estimation performs a similar feature as that obtained from still water experiment.     

海上溢油粒子追踪预测模型中的两种数值方法比较

在海上溢油粒子追踪预测模型中,关键的是对拉格朗日微分方程的求解。本文首先通过数值实验比较了欧拉法和龙格-库塔法求解拉格朗日溢油轨迹微分方程的优劣,然后将其应用到2005年4月3日发生在大连附近的“ARTEAGA”油轮溢油事故的油膜粒子追踪模型中。数值实验和应用结果表明,在近岸不均匀流场下,用龙格-库塔方法解拉格朗日油粒子微分方程比用欧拉法求解精度高,用龙格-库塔方法模拟“ARTEAGA”油轮轨迹及其扩散范围与实际观测更为接近,而用欧拉法模拟溢油扩散的面积偏大。     

咸淡水交汇区重金属粒径分配特征的模拟实验

利用从珠江莲花山河段采集的淡水和大洋海水经过滤后，按不同盐度混合，模拟河口咸淡水交汇区重金属在水中各微粒级的分配特征。实验结果表明，在各种盐度条件下，Ｆｅ，Ａｌ，Ｃｕ，Ｐｂ，Ｚｎ和Ｃｄ主要以粒径＞１．０μｍ和＜０．２２μｍ的微粒存在于水中。在加入Ｆｅ（３＋），Ａｌ（３＋）模拟实验中，重金属绝大部分含量形成粒径＞１．０μｍ的微粒，其中Ｆｅ达９９％以上，Ｃｕ，Ｐｂ约９５％，Ａｌ约有７０％－９０％，Ｃｄ约４０％，其余部分主要以＜０．２２μｍ微粒存在。加入与未加入Ｆｅ（３＋），Ａｌ（３＋）的实验比较，Ｆｅ（３＋），Ａｌ（３＋）的加入对水中Ｃｕ，Ｐｂ，Ｚｎ和Ｃｄ含量向大微粒聚集有很大影响，使其聚集在粒径＞１．０μｍ微粒的量增加３０％－４０％。另外从实验结果和理论分析可知，水的盐度与重金属在位径＜１．０μｍ微粒中的含量分布无明显关系，但咸水中大量离子将对河水中胶体絮凝和微粒增长有重大影响。     

Particulate n-alkanes and fatty acids in the Changjiang river system

Particulate samples were collected from the Changjiang river system during a flood period, in May 1997, and POC, stable isotope and lipids associated with particles were examined. Results showed the decrease (0.84% ～ 1.88%) of organic carbon content from the upper reaches to the estuary.δ13C values of particulate organic carbon was in the range of -24.9×10-3 to -26.6×10-3, which were close to the isotopic signature of continental C3 vegetation. Total particulate n-alkanes concentrations varied from 1.4 to 10.1μg/dm3,or from 23.7 to 107μg/g of total suspended matter. Fatty acids were present in all the samples, from 1.4 to 5.4μg/dm3, with saturated and unsaturated straight-chain and branched compounds in the carbon number range from C12 to C30. Both δ13C and the ratio of carbon content to nitrogen content indicate the predominance of terrestrial inputs (soil organic matter) among the particles. The biomarker approach has been used to identify the relative portion of terrigenous and autochthonous fraction in the particulate samples. The distribution of fatty acids suggests a striking phytoplanktonic and microbial signal in most particle samples. The terrestrial alkanes are used to estimate the contribution of terrestrial inputs along the mainstream.     

Numerical simulation of solitary wave propagation based on MPS method

The concept of candidate particle set is introduced in the MPS gridless numerical method to generate neighboring particle set matrix, which can reduce the CPU time to 1/11 of that before introduction. The Bi-CGSTAB (bi-conjugate gradient stabilized) algorithm is applied to solving the Poisson pressure equation, by which the solving speed is significantly accelerated. The process of solitary waves propagating over a numerical flume and interacting with a vertical wall is simulated. The simulated results of water surface elevation are in good agreement with the analytical solution as well as the measured data. The predicted maximum values of the run-up of solitary waves with various relative incident wave heights agree well with the measured results.     

Verification of linear theory for particle velocities in wind waves based on field measurements

Analyses are presented of field measurements of spectral transfer functions between surface elevation and subsurface three-dimensional particle velocity in wind-generated waves, in conditions ranging from young seas to old swells. The results are in agreement with the linear theory predictions to within the measurement error margin, which is estimated to be ± 5% for the gain functions and ± 4° in phase as far as the possible systemic errors are concerned. No correlation is found of the degree of agreement between measurements and linear theory with wave age or wave sleepness.