沿海深水岸段排污口近区污染物混合过程的模拟方法

本文提出一种将二维动态水质模型与三维稳态水质模型有机结合的新方法，用来处理沿海深水岩段排污口近区污染物混合问题，使之能较好地再现其客观混合过程，将这种方法应用于深圳大鹏湾某大型石化项目的环境影响预测中，结果令人满意。     

湖水总磷浓度的数学模拟

本文针对现行湖水总磷模型中的存在问题,探讨了均匀混合和非均匀混合两类湖泊总磷模型的建立方法。验算结果表明,不仅模型的计算精度能符合水质规划的要求,而且还较好地解决了大型浅水湖泊中总磷浓度分布的时空差异问题。     

上海市水源地水质综合评价方法的探讨

基于2005年至2007年上海市陈行水库和青草沙水源地的监测资料,应用基于组合权重法的水质综合评价模型对水质状况进行了综合评价。并将综合评价结果与单因子评价结果进行比较分析。研究结果表明:基于组合权重法的水质综合评价模型简便、适用,利用样本信息较为全面,能够实现对水质客观、准确、量化的分类和排序,是一种较为有效的水质评价方法。     

港湾三维水动力和污染物扩散数值模型

本文提出一种浅海三维污染物扩散数值模拟的方法。首先建立σ坐标系下的Navier-Stoker方程及物质扩散方程。基于过程分裂法将前者分解为外模式（二维方程组）及内模式（三维方程组）；并且引入窄缝法对变边界进行模拟，由此建立三维σ坐标潮流模型；并找到σ坐标系下三维污染物扩散方程的差分方法，最后建立三维σ坐标污染物扩散模型。本模型已被应用于厦门海域，并对其2002年海水水质（CODCr值增量)进行了预测。应用结果表明，这种三维可变边界污染物扩散数值模型能够较好地对具有较大面积浅海滩涂的海区进行水质模拟和预测。     

悬对沙Mellor-Yamada海洋边界层模型计算结果的影响

为了分析海洋水体垂向水流紊动及紊动交换情况而采用了一维的海洋边界层模型(Mellor-Yamada)并利用数值实验的方法对悬沙、盐度、温度等数据进行分析。原模型未将悬沙考虑在内，本文试将它引入进去探讨由于它的存在对紊动混合特性的影响。2000年4月，Mellor将最初的模型引入了依赖于Richardson数的紊动动能耗散率。本文通过比较具有悬沙和不具有悬沙两种情况下的速度、温度和盐度垂向分布随时间的变化，分析讨论由于悬沙的存在所引发的密度层化对紊动混合作用的影响，并发现悬浮泥沙抑制了部分模拟时间的紊动混合作用。     

基于资源一号数据的棋盘山水库水质信息提取

利用遥感技术对棋盘山水库进行水质信息提取,并根据水质状况进行相应的治理,对保证旅游区景观和水库内部生态环境稳定至关重要.利用资源一号02D卫星在短波红外谱段进行谱段细分的特点,在现有水质反演模型的基础上提取棋盘山水库的水质信息.为检验资源一号02D卫星数据的水质参数反演能力,将水质反演参数与主流卫星Sentinel-2...     

芽孢杆菌菌剂在水产养殖中的应用初探

应用两种芽孢杆菌为主导菌,对养殖水体中各项水质因子进行控制和处理。结果表明,两种芽孢杆菌无论是与啤酒酵母菌混合发酵还是单独发酵后投加入养殖水体中水质各项指标均优于对照池,达到养殖水体良好水质水平,NH3-N,NO2--N,COD等污染物浓度分别大约降低了96.97%,87.78%,73.66%,显著改善了养殖水体水质,芽孢杆菌与啤酒酵母菌混合培养发酵液效果略好于芽孢杆菌单独发酵作用。     

膜集成技术在海水养殖中的应用与探索

采用超滤、紫外辐射、臭氧氧化三种形式的多效滤除、混合协同作用，展示并模拟出了应用膜集成技术预防养殖用海水水质恶化的最佳技术路线，通过可行性试验表明，超滤膜过滤与臭氧氧化作用均有可靠的杀菌效果，组合工艺不但保持了养殖所需的盐氛围，且可以增加水中的溶解氧，净化水质，从而提高海水的重复利用率，节省能源。     

基于BP人工神经网络的海水水质综合评价

为了能够客观地对海水水质进行综合评价,在分析人工神经网络概念和原理的基础上,从阈值角度出发,通过对各类海水水质污染指标浓度生成样本的方法,生成了适用于BP人工神经网络模型训练的样本,并应用基于误差反向传播原理的前向多层神经网络,建立了用于海水水质评价的BP人工神经网络模型。将该模型用于渤海湾近岸海域水环境评价,通过模型...     

闽江下游河道排污口设置的水质响应分析

建立了闽江下游河道一维动态水质模型，探讨了北港不同排污口设置方案对南、北港分汉河道水质的影响．结果表明，北港排污不仅影响排污口附近及北港河道的水质，还影响到南港河道；两个排污口组合设置下的水质好于单个污染源设置情况：污染物浓度过程呈现周期性的变化，排污口河段以上断面，涨潮时污染物浓度增高，落潮时污染物浓度降低，排污口河段以下断面的则相反     

Practical spreading of driving forces for wave-driven currents

Profiles of wave-induced current on plane beaches are generally smooth. Previously, the smooth nature was often explained by involving lateral mixing concept. This paper describes a new spreading approach instead of the previous lateral mixing approach. The spreading of the driving forces leads to similar results on the velocity profiles of the previous approach. The results of the new method show good agreement with some laboratory measurements for a plane beach. The present method was then extended for two-dimensional plan problems. The present approach was tested against a laboratory experiment, and the computed flow field agrees reasonably well with the measured flow field. A merit of the present method is that the computational time increment is not restricted by the lateral mixing.     

异常事件对EMD方法的影响及其解决方法研究

作者指出异常事件在数据中形成局部的高频信号 ,运用经验模态分解 (EMD)方法分析这种存在异常事件干扰的数据 ,就会产生本征模函数 (IMF)的频率混叠现象 ,而造成物理过程的重叠 ,使得难以用时间过程曲线表现特定的物理过程。这一问题是 EMD方法中尚未妥善解决的问题。为解决这一问题 ,作者利用干扰信号极值及其两边的极大与极小值位置与原始数据有明显对应关系的特征 ,将相关 IMF中的异常信息直接滤除 ,再用 Spline插值方法弥补滤除时段的数据 ,得到重新拟合的该 IMF数据。采用这种方法可以提取出异常信号 ,提取的精度与异常信号的时段长度有关。而且 ,拟合结果消除了异常干扰 ,可以将该 IMF与其余 IMF一起叠加成没有异常干扰的数据。将滤除了异常干扰的数据再次进行 EMD分解 ,可以得到新的 IMF系列 ,而它与不加校正的分解结果有相当大的差别 ,可靠地反映了真实物理过程。结果表明 ,只有在有效滤除异常干扰的情况下才能获得可靠的 IMF系列 ,并准确地描述各种尺度的现象 ;消除了异常干扰的 IMF可以任意单独或组合使用 ,表现各种时间尺度的变化与过程 ;所讨论的方法只适合异常时段较小的情形。对于异常时段接近或大于正常变化周期的干扰还需要探讨其他方法     

海底热液硫化物矿体内部流体混合过程的数值模拟:以大西洋TAG热液活动区为例

大型海底热液硫化物矿体的形成机制是涉及多种控制因素的复杂地质过程,其中热液流体同海水的混合扮演着重要角色。大洋钻探计划(ODP)资料表明在大西洋TAG区热液硫化物矿体内部,热液流体同经过改造的海水之间发生着广泛的混合作用,这个过程在很大程度上控制着海底热液硫化物矿体的内部结构和化学组成。以TAG热液硫化物矿体为例,利用数值模拟方法模拟了热液流体与经过不同程度改造的海水的混合过程,试图探讨海水与热液流体混合在热液硫化物矿体形成中的作用。模拟计算结果表明:(1)来自矿体深部的热液流体与经围岩加热的下渗海水的混合是造成TAG热液活动区硬石膏大量沉淀的重要原因;(2)在热液流体与海水的混合过程中,混合流体的化学性质和矿物沉淀情况在330~310℃上下发生了较大变化,330~310℃是一个特殊的温度区域;(3)利用数值计算结果探讨了TAG热液活动区不同区块(TAG-1,TAG-2和TAG-5等)的流体混合作用和热液活动过程。     

Comparative quantification of physically and numerically induced mixing in ocean models

A diagnostic method for calculating physical and numerical mixing of tracers in ocean models is presented. The physical mixing is defined as the turbulent mean tracer variance decay rate. The numerical mixing due to discretisation errors of tracer advection schemes is shown to be the decay rate between the advected square of the tracer variance and the square of the advected tracer and can be easily implemented into any ocean model. The applicability of the method is demonstrated for four test cases: (i) a one-dimensional linear advection equation with periodic boundary conditions, (ii) a two-dimensional flat-bottom lock exchange test case without mixing, (iii) a two-dimensional marginal sea overflow study with mixing and entrainment and (iv) the DOME test case with a dense bottom current propagating down a broad linear slope. The method has a number of advantages over previously introduced estimates for numerical mixing.     

河水与海水混合过程中Eh-p H的变化特征及影响因素

河口是河水和海水混合地带,河口地区每时每刻都在发生复杂的物理、化学、生物作用,该过程中水体Eh、pH参数的变化直接关系到氧化还原元素的行为以及重金属、有机污染物的迁移、转化和清除.本研究采集了长江河水、东海陆架海水,设置了盐度为5、12.5、25的3组混合实验,模拟长江河口水体混合过程,实时测定混合过程中水体Eh、pH...     

A new mixing technique for solidifier and dredged fill in coastal area

One of the major drawbacks of the conventional method of land reclamation, which involves mixing cement with the dredged soils at the disposal site, is the high cost associated with its manufacturing and transportation. In this study, a new solidified dredged fill (SDF) technique and a new additive are proposed and their practical applications are discussed. Unlike the conventional approach, the dredged marine soils were mixed with the solidifiers using a newly designed mixing technique prior to its transport to site, which would significantly reduce the cost of site machinery and effectively reclaim land with adequate engineering properties necessary for the construction of infrastructure. To evaluate the performance of the reclaimed land using the proposed technique, a series of laboratory and field tests (namely, static and dynamic cone penetration tests, and plate load tests) were conducted on grounds filled with and without solidified dredged marine soils, respectively. The results showed that the engineering behavior of the reclaimed land with dredged marine soils using SDF technique had significantly improved. The SDF technique combined with the newly designed mixing system improved the performance of ground and has thus proved to be both cost-effective and safe.     

Physical processes associated with high primary production in Saanich Inlet, British Columbia

Saanich Inlet, British Columbia, has long been known for the presence, in most years, of anoxic bottom water. One factor contributing to this anoxia is a high level of primary production, which occurs as a major spring bloom followed by sporadic ‘mini-blooms’ throughout the summer and early fall. The process(es) by which new production is refueled after nutrient exhaustion caused by the spring bloom are not well known, since Saanich is an inverse estuary and vertical mixing driven by winds and tides is low. This study presents new observational evidence that strongly suggests that the dominant mechanism of nutrient resupply during the summer months is intermittent advective exchange, driven by pressure gradients set up by strong tidal mixing in passages outside Saanich Inlet itself. A simple box model is formulated to illustrate this mechanism. When driven by annual freshwater forcing and deepwater renewal functions characteristic of the region and measured tides for 1975, the model predicts resupply of nitrate during most of the periods observed in 1975 observations (Deep-Sea Res. 24 (1977) 775). This ‘action-at-a distance’ nutrient resupply mechanism, involving strong but localized turbulent mixing and subsequent distribution of the products of mixing over large-horizontal distances by pressure-gradient-driven flow, is likely important in other coastal regions where the estuarine circulation is weak.     

Assessment of Unconfined Compressive Strength of Cement Stabilized Marine Clay

Two aspects of deep mixing method, the difference relating strength gain in dry jet mixing (DJM, reagent powder introduced into the ground) and cement deep mixing (CDM, reagent slurry introduced into the ground), and prediction of unconfined compressive strength of cement stabilized marine clay, are discussed in this paper. The first part of this paper concentrates on the difference between DJM and CDM on strength gain, and suggests a guideline for DJM and CDM selection. An indicator in terms of water content ratio, which is defined as the ratio of water content to the liquid limit of the soil, is presented by statistical analysis from the laboratory and field test data as a guideline for the selection of DJM or CDM. Based on the laboratory test data, a mathematical model relating strength gain of cement stabilized marine clay to related variables is developed. A new simple index designated as total water-cement ratio, which is defined as the ratio of water weight in the soil-cement to the weight of cement in dry state, is proposed for interpretation of test data of soil-cement. The proposed method is then verified with available test data published by other different researchers.     

Assessment of Unconfined Compressive Strength of Cement Stabilized Marine Clay

Two aspects of deep mixing method, the difference relating strength gain in dry jet mixing (DJM, reagent powder introduced into the ground) and cement deep mixing (CDM, reagent slurry introduced into the ground), and prediction of unconfined compressive strength of cement stabilized marine clay, are discussed in this paper. The first part of this paper concentrates on the difference between DJM and CDM on strength gain, and suggests a guideline for DJM and CDM selection. An indicator in terms of water content ratio, which is defined as the ratio of water content to the liquid limit of the soil, is presented by statistical analysis from the laboratory and field test data as a guideline for the selection of DJM or CDM. Based on the laboratory test data, a mathematical model relating strength gain of cement stabilized marine clay to related variables is developed. A new simple index designated as total water-cement ratio, which is defined as the ratio of water weight in the soil-cement to the weight of cement in dry state, is proposed for interpretation of test data of soil-cement. The proposed method is then verified with available test data published by other different researchers.     

Cross-Frontal Water Exchange on Georges Bank: Some Results from an U.S. GLOBEC/Georges Bank Program Model Study

This paper reviews recent progress on modeling cross-frontal water exchange on Georges Bank undertaken as part of the U.S. Global Ecosystem Northwest Atlantic/Georges Bank Study (U.S. GLOBEC/Georges Bank Program). A simple conceptual model is described first, followed by a discussion of four physical mechanisms associated with (1) strong nonlinear interaction, (2) asymmetric tidal mixing, (3) varying wind forcing, and (4) chaotic mixing. Some critical issues in modeling studies of fronts are also addressed. A new unstructured grid, finite-volume coastal ocean ecosystem model is introduced. This model combines the best of the finite-difference method for the simplest discrete computational efficiency and the finite-element method for geometric flexibility. Because the finite-volume method discretizes the integral form of the governing equations, this approach provides a better representation for the conservation laws of mass and momentum are satisfied, which is particularly important in the frontal regions. This revised version was published online in August 2006 with corrections to the Cover Date.