海岸带是陆地、海洋和大气相互作用最强烈的地带,也是受全球气候、海平面变化以及人类活动影响最大的地区.海岸带动力过程具有明显的海洋-陆架-海湾-海岸多尺度多物理场特点,动力地貌过程和响应机制极具特色.台风等极端气象事件的频繁发生,工程措施等强人类活动的影响,导致海岸带动力地貌演变规律呈现出更大的不确定性.从高强度扰动下海岸动力条件、极端条件影响下海岸动力地貌特征和强人类活动影响下海岸动力地貌特征等方面,综述了已有研究工作进展.全球气候变化和人类活动共同作用的海岸带多尺度动力过程和海岸地貌响应内在机制极其复杂,在未来海岸动力地貌特征的研究中,需要进一步从大气、海浪、海洋和泥沙等多物理场,海洋、陆架、海湾和海岸等多尺度,动力条件、泥沙输移和地貌塑造等多过程的角度,探究高强度扰动下海岸带动力过程、响应机制和演变规律.

Based on the measured topography data of Dongting Lake in 2003 and 2011, a previous calibrated 2D hydrodynamic model was adopted to simulate the impact of lake topographic change on the flood process of Dongting Lake using the 2003 flood as an example. The results show that over 40% topography of the lake subsided more than 0.10 m, especially the Xiangjiang spillway, the topography of its talweg subsided by 5.72 m. According to the simulation of the 2003 flood process, when the flood process was dominated by the Four Rivers, the flood peak water level decreased by more than 0.40 and 0.20 m in the South and West Dongting Lake under the topographic condition of 2011 compared with that of 2003; but for the East Dongting Lake, the water level only decreased significantly in the southern area with large topographic changes. The water surface gradient decreased in the Doumizui-Chenglingji section, but increased in the spillway of the South Dongting Lake. For the flood process dominated by the inflow of the Yangtze River, the flood peak water level in Dongting Lake decreased by 0.15 m, and the water surface gradient changed little in the Doumizui-Chenglingji section and the South Dongting Lake, due to the jacking effect of the Yangtze River. Therefore, the topographic change in Dongting Lake from 2003 to 2011 has a great impact on the flood dominated by the inflow of the Four Rivers, which can effectively alleviate the flood control pressure in Dongting Lake because the entrenchment of the lake basin increased the storage capacity of the lake; however, it has little impact on the flood dominated by the inflow of the Yangtze River. The research results can provide a reference for the implementation of flood control measures such as dredging and capacity expansion in Dongting Lake.

沉降速度是珊瑚砂的一个重要物理参数.由于柱状珊瑚砂与其他形状的珊瑚砂有着明显的差异,套用现有珊瑚砂的沉速公式进行计算并不合适.本文选取柱状珊瑚砂进行单颗粒沉降试验,研究静水中柱状珊瑚砂沉降速度及其影响因素,通过讨论分析不同的等效粒径和形状系数对柱状珊瑚砂沉降速度的影响,发现柱状珊瑚砂的沉降速度与等容粒径和Corey形状系数密切相关,基于本文试验数据推求了适用于计算柱状珊瑚砂沉降速度的经验公式,丰富了海岸泥沙理论.

The double row perforated cylinder breakwater is a new composite structure based on the cylinder and plate breakwater. The three-dimensional numerical wave flume is established based on the incompressible two-phase flow model. The turbulent closure is carried out by RNG k-ε turbulence model, and the Tru VOF method is used to capture the free liquid surface. The influence of relative row spacing and opening rate on the wave dissipation performance of double row perforated cylinder breakwater is explored, and the special hydrodynamic phenomena and flow characteristics near the back row perforated cylinder breakwater are analyzed. The results show that in the range of working conditions studied in this paper, the along-range average wave height increases and then decreases with the increase of relative row spacing, and increases with the increase of opening rate, and the effect of period on the along-range average wave height has no obvious rule; when B/D = 9, e = 23.11%, the double row perforated cylinder breakwater has the best wave dissipation effect, the reflection coefficient ranges from 0.4 to 0.46,the transmission coefficient is between 0.3 ～ 0.35, the dissipation coefficient is between 0.8 ～ 0.85. Free surface fragmentation, water-air mixing and annular eddy motion evolution are the main causes of wave dissipation and energy dissipation of double-row cylinder breakwater. The jet stage occurred more violent free liquid surface fragmentation and water-gas mixing, resulting in the increase of turbulent kinetic energy after the dike, the peak turbulent kinetic energy after the increase is about 2.5 times of that before the jet,and the violent turbulent energy dissipation occurred. The relative row spacing will cause the changes of vorticity distribution and shear layer morphology near the rear breakwater, which will lead to different turbulent characteristics and affect the wave breaking characteristics of the double row perforated cylinder breakwater. The research results can provide theoretical support for the engineering design of a new type of double-arranged cylindrical breakwater and the study of wave dissipation mechanism.

基于二维不可压缩两相流模型建立了数值风浪水槽,采用SSTk-ω雷诺时均湍流模型,研究了风作用下孤立波在珊瑚礁上的传播变形规律.将计算结果与实验数据对比,证明了该两相流模型计算孤立波在珊瑚礁上传播的准确性,并进一步分析了不同风速对珊瑚礁上孤立波传播变形的影响.结果表明:风的作用会使波面发生随机脉动特征,当地波高随风速的增大而增大;当地波高关于风速的变化梯度随入射波高的增大而增大.风的作用会加快孤立波的传播并且使孤立波提前发生破碎;孤立波开始破碎的位置随风速的增大而向远离礁坪的方向移动.反射系数随风速的增大而增大,反射系数关于风速的变化梯度随入射波高的增大而减小;透射系数随风速的增大呈增大趋势.平底区波峰剖面同一水深处的水平流速随风速的增大而增大,且一定的风速不改变水平流速沿水深的变化梯度.有风时波面上方的矢量密度和大小均明显高于无风时且与风速呈正相关,并且波峰上方气流不再循环.随着风速的增大,水气界面附近的正涡量和负湍流剪应力减小,负涡量和正湍流剪应力增大.水体动能、势能和总能达到高值的时间随风速的增大而减少;水体动能、势能和总能随风速的增大而增大,并且风速对水体动能的相对影响大于势能.

为提高磷酸钙结晶产物回收价值和低磷适应性,以羟基磷酸钙(HAP)为晶种,诱导Ca-P结晶回收模拟二级出水(初始PO4-P浓度1.0mg/L)中的磷,对比了诱导结晶与均相结晶的磷回收效果,考察了Ca/P比和晶种投加量对磷回收的影响,并结合产物SEM、EDS、XRD和FTIR分析,探讨了HAP诱导Ca-P结晶机制.结果表明,HAP诱导Ca-P结晶在避免晶种材料对结晶产物纯度和品质影响的同时,还具有低磷适应性强和启动快速的优势;Ca-P结晶模式包括构晶离子在HAP表面的逐层结晶模式和在HAP颗粒空隙间的晶桥模式.实验条件下,模拟二级出水磷回收率可达80％以上,产物包括HAP及其前体物ACP(无定形态磷酸钙)和OCP(磷酸八钙).Ca-P结晶过程伴随发生CaCO3结晶,干扰磷结晶回收.研究成果为低磷污水磷回收率和回收产物品质的提升提供了依据.

本文利用粒子图像测速系统和浪高仪对3种概化岸坡下破碎区至冲泻区的波高、流速等水动力学参数进行实验测量,并基于二阶谱方法分析波高和流速的概率密度分布,统计了破碎区至冲泻区内波高和流速的偏度、不对称度、峰度等高阶非线性变量.结果表明:破碎区至冲泻区内的波高和流速均偏离正态分布,波高偏度和峰度在向近岸传播过程中先减小后增大,不对称度先增大后减小,波高的非线性特征受坡度影响不大.3种工况下流速表现出不同的非线性分布特征,在陡坡和复合坡中,各断面流速偏度分布特征不明显,而在缓坡中各断面流速偏度的垂线分布自床面到自由水面呈现先增大后减小的特征;3种工况下流速的不对称度随距床面距离的增大均呈现先增大后减小的变化趋势.

为探讨船行波对通航隧道断面尺寸的影响,基于完全非线性Boussinesq方程的开源程序包FUNWAVE-TVD建立了通航隧道内船行波传播的数值模型,重点分析了通航隧道内最大船行波波高及横向流速的时空分布规律,探讨了船舶吃水深度、弗劳德数、通航隧道水深和宽度以及船型对通航隧道内最大船行波波高和横向流速的影响;基于船行波波高历时分析,提出了计算通航隧道垂向断面高度的经验公式,并结合船行波破碎生成的横向流速和现行内河通航标准,给出了通航隧道内安全航行的水流条件及隧道横向断面尺寸的设计建议.结果表明:受隧道两侧直立壁反射影响,船尾波易受通航隧道岸壁影响叠加形成较大波高,越靠近隧道岸壁位置,最大横向流速越小;当船舶达到设计吃水深度时,产生的船行波不易破碎,最大横向流速较小.

微塑料是目前环境领域备受瞩目的新兴污染物,其污染监测基础数据仍存在许多空白亟待填补.本研究选择典型城市湖泊岳阳南湖为研究区域,对其表层水体微塑料污染进行研究.本研究在14个遍布南湖各个区域的采样点采集表层水体样品,基于湿式消解和密度分离方法对样品进行处理,并采用体视显微镜和显微红外光谱仪进行鉴定,对该区域45 μm—5 mm范围的微塑料污染水平、分布特征、潜在来源及风险进行探讨.研究结果表明,南湖表层水体微塑料丰度在3050-7100 n·m-3之间,平均值为(4664±1742)n·m-3,其污染水平高于大多数自然湖泊,与武汉、长沙等城市湖泊相当;南湖表层水体中的微塑料更容易集中于湖泊中央区域,微塑料在南湖表层水体中的分布呈现"中高边低"的特点;南湖中检测到的微塑料以纤维状为主,其化学成分主要为聚乙烯、聚酰胺和聚对苯二甲酸乙二醇脂.由此可知,居民日常生活、旅游业、渔业是南湖微塑料的潜在来源;南湖表层水体微塑料的分布受到水动力条件影响显著;同时,研究区域对于碎片和微球微塑料的管控措施较为有效,而纤维微塑料仍大量赋存于南湖之中,这种情况需要得到重视,微塑料污染防控措施在未来需要进一步完善.

In this work, a series of Ag3PO4/g-C3N4 (AG) photocatalysts were synthesized. After characterizing the properties, the effects of mass ratio, light intensity, and material dosages on photodegradation were investigated. The material with a 1/2 mass ratio of Ag3PO4/g-C3N4 showed the highest photocatalytic activity under visible light, and the removal efficiency reached 90.22% for an initial suspended algae concentration of 2.7 × 106 cells/mL, 0.1 g of AG, and 3 h of irradiation. These results showed that the conductivity was increased while the total protein and COD contents of the algae suspension were declined rapidly. In contrast, the variations in the malondialdehyde (MDA) level suggested that the algae cell wall was severely damaged and that selective permeability of the membrane was significantly affected. A possible photocatalytic mechanism was proposed and •O2− was shown to be the major reactive oxygen species in the photocatalysis. In summary, during the visible light photocatalytic process, the cell structure was destroyed, which caused the leakage of electrolyte, the inactivation of protein, and the inhibition of photosynthesis; finally, the cells died. This study provides a reference for photodegradation of algae pollution in water bodies.

基于开源程序REEF3D,通过建立高精度二维数值波浪水槽,系统研究了聚焦波浪在浅堤上传播变形的规律,着重分析了聚焦波浪通过浅堤的水动力过程及能量变化规律,讨论了不同波浪要素对聚焦波浪传播特性的影响.除此之外,还考虑了双浅堤布置对聚焦波浪传播变形的影响.研究结果表明:极端波浪通过浅堤时,堤顶水深越小,波浪主频能量衰减越显著.在给定堤顶水深条件下,聚焦点与浅堤的相对位置对聚焦波浪能量的衰减影响较小.在双浅堤布置条件下,随着浅堤间距的增加,上下游浅堤的相互影响逐渐减弱,高频段的波浪能量也随之减小.

以絮状污泥作为接种污泥,通过改变进水氮硫比(N∶S)培养好氧颗粒污泥,考察其对污泥颗粒化的影响及反应器内COD、氮、磷浓度的变化,并利用微生物基因测序手段分析微生物群落结构的变化.结果 表明,当N∶S为2∶1和4∶1时,污泥处于连续膨胀状态,无法形成颗粒,此时MLSS为1.104 ～3.647 g/L、SVI5为137～416 mL/g、SV5为40％ ～ 60％.当N∶S升至8∶1时,污泥流失得到控制,并在第72天时培养出成熟的好氧颗粒污泥,其粒径主要分布在0.4 ～0.8 mim,此时MLSS为3.27 ～ 5.17 g/L、SVI5为36 ～ 67 mL/g、SV5为12％～20％.污泥颗粒化后,对COD、NH4-N、TN、TP的平均去除率分别达到95.51％、99.62％、61.30％、25.62％.而整个培养过程中,对硫化物的去除率可达到99％.对成熟颗粒污泥进行微生物群落多样性检测,结果表明,颗粒污泥中Paracoccus、Meganema、Azoarcus为优势菌属,隶属于变形菌门.

Agricultural processing by-product have been used as the feed stock for effluent treatment to promote the utilization of agricultural waste, the development of green sustainable and construct a green ecological circle nowadays. Based on camellia oleifera shells, attapulgite, and ferric chloride, a novel iron oxide loaded biochar/attapulgite composite (Fe-BC/A) was synthesized via a one-step pyrolysis process and as a low-priced and efficient adsorbent for Cr(VI) removal from aqueous solution. The structure and composition of Fe-BC/A were characterized by SEM-EDS, FT-IR, XRD, and XPS, which confirmed iron oxide (analogous to alpha-Fe2O3 and beta-FeOOH) and attapulgite clay were successfully incorporated with biochar. The maximum adsorption capacity of Cr(VI) by Fe-BC/A was 107 mg/g at pH 2.0, which was much higher than the original biochars (BC: 54.38 mg/g) and biochar/attapulgite composites (BC/A: 81.75 mg/g). The adsorption behavior of Fe-BC/A fitted better with pseudo second-order model and Freundlich model, which indicated that multilayer chemisorption might dominate Cr(VI) adsorption. The thermodynamic analysis of Fe-BC/A represented that removal of Cr(VI) was a spontaneous and endothermic process. Batch experiments results demonstrated that Fe-BC/A had great adsorption capability of Cr(VI) in a broad pH extent of 2.0-10.0, whose most favorable elimination for Cr(VI) at pH of 2.0 and the removal efficiency of Cr(VI) was about 80% at pH = 10 (C-0 = 100 mg/L, 30 degrees C). Fe-BC/A exhibited a prominent tolerance to the coexisting ions during Cr(VI) removal and only a slight decrease (8.27%) in elimination efficiency after five adsorption-desorption cycles. Mechanism study revealed that electrostatic attraction, reduction, anion exchange, and complexation were involved in the removal of Cr(VI). This study implied the potential practical application of Fe-BC/A in the future Cr(VI) remediation from wastewater.

南沙岛礁的发育受空间位置、暴露面积及地质结构等因素的影响,礁体的演变伴随空间形态的变化.本文利用遥感和地理信息系统(GIS)相结合的方法绘制南沙岛礁核密度现状图,并采用Kernel Density进一步分析南沙礁群空间核密度分布.研究表明:南沙岛礁空间形态复杂,有明显区域格局性,面积差异较大的岛礁核密度聚集位置不相同,分布特征相对密集.岛礁数量在纬度方向有明显浮动,在经度方向上趋于稳定.随礁体面积的增大,礁体平均形状指数逐渐增大,平均紧凑度逐渐减小,形状指数LS1介于0.90～ 2.87之间、紧凑度RC介于0.31～ 0.97之间.研究结果有助于更好地了解南沙岛礁密度情况,为海洋管理人员提供参考信息.

[目的]研究海啸波在斜坡海堤上越浪的水动力特性.[方法]基于非静压模型NHWAVE建立高精度二维数值波浪水槽,通过对日本2011年实测真实海啸进行参数化形成类海啸波形,并设置系列计算工况,深入分析入射波高、水深、岸滩坡度及海堤坡度对类海啸波作用下海堤越浪特性的影响,并将计算结果与孤立波进行对比.[结果与结论]相同工况下,类海啸波的单宽越浪量大于孤立波,波浪经海堤消能后,能量衰减,孤立波能量损耗率大于类海啸波;随波高和水深增加,越浪量均增大;海堤坡度对越浪量的影响不大;岸滩坡度减缓,波浪速度将在堤前聚集,类海啸波在1:20的岸滩坡度下越浪量达到最大.研究结果可为近岸水利防护工程的建设提供参考.

在低有机负荷区间(1.2～3.6 kg/(m3·d))内升降有机负荷率(OLRs),探究其对好氧颗粒污泥(AGS)的形成及污染物的去除影响.结果表明:连续提高OLRs,可促进颗粒污泥形成系统生物量增加;AGS形成过程,TP与TN去除效果逐步提高至98.75％与91.40％,且COD与NH+4-N去除率均高于95％.连续降低OLRs时,大颗粒污泥出现裂解,TP与TN去除率降低;碎片再颗粒化时,TP去除率有上升趋势,而TN去除率随OLRs降低而降低.微生物多样性检测结果表明:OLRs波动系统培养出的优势菌为Paracoccus、Meganema,而其他类菌属相对丰度缩小,反应器内的生态系统变得脆弱.

长江源区河网水系密布且广泛发育辫状河道,由于地形资料匮乏,尚缺少其形态表征的研究报道.利用UAV航测与实地观测相结合的方法,获取长江源楚玛尔河、沱沱河、布曲-1、布曲-2等4条河流的数字正射影像(DOM)和数字地表模型(DSM).基于实测河道地表形态空间变化,计算洲滩与水域面积比值在0.638～2.152区间,水域与河床面积比值在0.317～0.611区间.对比不同河段辫状指数的关联性,表明辫状指数可用于判断辫状河段的复杂程度,并且其数值越大,反映复杂程度越高.截取平均横截面拟合曲线定义平均横截面形状,表明4条辫状河段(α＞l)均为凹形向下的Y型截面.

为研究珊瑚礁坪上采掘坑位置变化对珊瑚礁海岸波浪传播变形的影响,本文通过物理模型试验测试了采掘坑在不同位置和无坑情况下一系列不规则波工况的波浪特征.结果表明,随着采掘坑位置朝岸线附近移动直至无坑时,岸线附近的短波波高逐渐减小;采掘坑的存在减弱了岸线附近的低频长波波高,当采掘坑位于岸线附近时,长波波高还受到局部水深增加的影响而进一步减弱.采掘坑从礁缘移动至岸线附近直到无坑时,岸线附近的增水逐渐增大,这种趋势在礁坪水深较大时更为明显.通过相干函数分析,证明了礁坪上低频长波是由于短波群破碎点的移动而产生,采掘坑位置的变化对低频长波的产生无明显影响;通过传递函数分析,验证了礁坪上的低频长波存在一阶共振放大效应,采掘坑的存在减弱了这种放大效应,当坑位于礁坪中间和岸线附近时,这种减弱效应更为显著.

为改善饮用水藻类的混凝去除效果,以铜绿微囊藻为研究对象,考察了单独投加Ca2+、Ca2+与PAC联用、Ca2+与CO32-原位结晶三种方法的除藻效果,并对Ca2+和结晶产物CaCO3的除藻机制进行探讨.结果 表明,单独采用Ca2+时,Ca2+在低浓度下对藻细胞具有吸附电中和作用,高浓度时同时还有架桥作用,但两者均无法实现对铜绿微囊藻的去除.Ca2+与PAC联用,Ca2+可以通过吸附电中和显著提高PAC的除藻效果,最大去除率可达98.0％,同时Ca2+与溶解性藻源有机物(dAOM)的络合可将残余铝降低50％以上.含藻水中原位CaCO3结晶对铜绿微囊藻的去除率最高可达83.5％,其产物为带正电荷、粒径2～4 μm左右的球型球霰石.球霰石对藻细胞的去除机制包括球霰石与藻细胞的互絮凝,以及球霰石团聚物对藻细胞的卷扫絮凝,同时球霰石还可以作为加重剂促进藻晶产物沉降分离.自来水厂采用CaCO3原位结晶与PAC联用除藻,可望降低PAC投加量和残余铝风险,并解决CaCO3原位结晶导致的浊度和pH偏高问题.研究成果为饮用水除藻提供了新思路.

为了研究双自由度子母管线周围的绕流特征,本文采用高精度浸没边界方法模拟了不同布置条件下双自由度子母管线的涡激振动特性,探讨子母管线质量比、间距比、空隙比和角度对子母管线低雷诺数振动特性及水动力的影响.结果表明:随着子母管线的质量比和间距比的增大,管线涡激振动的最大振幅逐渐减小,发生锁定的区间也变窄.不同角度对子母管线涡激振动的抑制作用不同,子管与母管并列时对子母管线涡激振动的抑制作用更强.另外通过对流向和横向耦合振动的分析可发现,低质量比时流向振动对横向振动的振幅和频率影响较大,而高质量比时这种影响相对较小.