内蒙古河套灌区3种沉水植物种子休眠及萌发特性     

王譞  李青丰  胡杨  贾红梅  李玲玲 《湖泊科学》2013,25(1):115-118

沉水植物在湖泊生态系统中具有重要作用,它不仅是湖泊生态系统食物链中重要的生产者,同时还对湖泊的营养物沉积和循环有着重要的意义,并由此影响着湖泊的富营养化进程.本文以黄河内蒙古段河套灌区湖泊中常见的3种沉水植物篦齿眼子菜(Potamogeton pectinatus)、穿叶眼子菜(Potamogeton perfoliatus)和狐尾藻(Myriophyllum verticillatum)为研究对象,对其种子休眠及萌发特性进行了初步研究.结果表明:狐尾藻种子休眠率较高但休眠易破除,通过切破种皮、低温层积、硝酸钾和赤霉素处理均可显著提高萌发率;篦齿眼子菜种子休眠性较强,低温层积及赤霉素浸泡处理能够显著提高其萌发率;穿叶眼子菜有较深的休眠特性,破除硬实、硝酸钾、赤霉素及低温层积处理均不能有效解除其休眠.  相似文献   

Vertical velocity distributions through and above submerged,flexible vegetation     

《水文科学杂志》2013,58(4):905-920

Abstract

A one-dimensional steady-state model was constructed and used to study vertical profiles of longitudinalvelocities in open channel flows through, and above, submerged vegetation. The eddy viscosity was evaluated by using the analogue of the mixing length theory. The model of water velocity profiles takes into account the surface roughness of the channel bottom and the drag exerted by submerged flexible stems. The verification of the calculated velocity profiles was carried out based on data obtained in laboratory experiments. The proportionality coefficients for the analogue of the mixing length formulae in both layers—within homogenous flexible stems and above them—were determined.  相似文献   

上海淀山湖水生高等植物现状及其近30年变化   总被引：2，自引：0，他引：2  

施文  刘利华  达良俊 《湖泊科学》2011,23(3):417-423

于2009年8月至2010年5月调查淀山湖水生高等植物现状.并结合历史资料分析其近30年变化,探讨水生植被的发展趋势及退化原因.淀山湖现有水生高等植物29种,隶属18科,25属,栽培种、外来种比例较过去升高.30年来水生植被(尤其是沉水植被)面积严重萎缩,主要植被类型从沉水植物占优势转变为漂浮植物占优势,沉水植被主要优...  相似文献   

GIS技术在洪湖环境演变研究中的应用   总被引：9，自引：0，他引：9  

俞立中  许羽  蔡述明  张晓阳 《湖泊科学》1993,5(4):350-357

本文运用GIS技术,探索了洪湖环境的近期变化及其机理,以空间的、定量的形式,展示了与修建隔堤、分割湖区、围湖垦殖及水位控制等人为活动因素相联系的湖泊环境变化效应和过程,分析了湖中挺水植物分布的动态变化与趋协。这项工作进一步表明了地理信息系统方法在湖泊环境变化的监测、评价和研究中具有独特的功效和实用价值。  相似文献   

Population variations in the grazing turbinid Lunella smaragda (Mollusca: Gastropoda)     

John R. Walsby 《新西兰海洋与淡水研究杂志》2013,47(2):211-238

The grazing turbinid gastropod Lunella smaragda was sampled regularly over 3.5 y from precise sites of different microtopography and height on the platform shore at Goat Island Beach near Leigh, Northland, New Zealand. Growth is linear for over 3 y, and the year‐classes distinct. The position of the different size‐classes is related to both the shelter afforded by the microtopography, and to the height on the shore. The populations in the mid‐eulittoral turf flats, low eulittoral bare rock areas, and the sublittoral fringe are distinct, and there is a general movement down the shore with age and size. Wave action apparently dislodges the animals from higher areas when they grow to a critical size and transports them to sites lower on the shore, where wave disturbance is less. Field experiments with marked animals and laboratory studies with a wave tank confirm that the wave‐effected distribution is size related. However measurements showed that the ratio of foot attachment area to the shell area presented to the wave does not vary with animal size. The possible benefits of wave dislodgment and wave‐effected distribution are considered.  相似文献   

Relationship between turbidity and fish diets in Lakes Waahi and Whangape,New Zealand     

John W. Hayes  Martin J. Rutledge 《新西兰海洋与淡水研究杂志》2013,47(3):297-304

Abstract

Stomach contents of Gobiomorphus cotidianus,Retropinna retropinna, Gambusia affinis, and Anguilla australis were compared between two shallow lakes in the lower Waikato River basin, to examine the relationship between turbidity and diet. Lake Waahi and the south arm of Lake Whangape had been turbid (20–40 g suspended solids (SS) m^?3) and devoid of submerged macrophytes since the late 1970s and early 1980s, respectively. The main basin of Lake Whangape had been generally clearer (5 g SS m^?3) with dense beds of submerged macrophytes, but at the time of sampling (1987) water clarity had deteriorated (> c. 10 g SS m³) and submerged macrophytes had declined. The mysid Tenagomysis chiltoni was an important prey for all species of fish from turbid water bodies but was less important in stomachs of fish in the main basin of Lake Whangape. Apparently, mysids were not an important prey in Lake Waahi before it became turbid. Chironomid larvae and pupae dominated the diets of small fish in the main basin of Lake Whangape. Fish and mysids were the most important prey of shortfinned eels in both lakes, with mysids most important in Lake Waahi. High mysid densities in the turbid water bodies provide an alternative food resource apparently compensating for those lost by fish when water clarity declined and submerged macrophytes collapsed.  相似文献   

Parametric study for underwater blast-induced pipeline response embedded in marine sediments     

C. C. Liao  Yaguang Wang  Qi Zhang 《Marine Georesources & Geotechnology》2013,31(9):1071-1082

Abstract

Blast response of submerged pipelines has been a research focus in recent years. In this article, a three-dimensional numerical model is established to investigate dynamic response of pipelines due to underwater explosion. The u–p approximation is integrated into finite element method (FEM) to simulate pore water effect in the seabed. Numerical continuity between hydraulic pressure in the flow field and pore pressure in the marine sediment is guaranteed to realize the blast response of submerged pipelines in ocean environment. Both fluid–structure interaction (FSI) and pipeline–seabed interaction (PSI) have been considered in the proposed model simultaneously. A comprehensive parametric study is carried out after validation of the present model with test data from underground explosion and underwater explosion, respectively. The effect of embedment depth, TNT equivalent, stand-off distance, pipeline diameter, and pipeline thickness to blast response of the submerged pipelines is investigated based on numerical results. Variation of deformation patterns and stress distribution of the pipeline with various installation and structure parameters has been illustrated and discussed to facilitate engineering practice.  相似文献   

开敞式滩海油田保滩促淤工程研究   总被引：3，自引：1，他引：2  

蒲高军  张日向  廖绍华 《海岸工程》2005,24(2):20-29

分析了飞雁滩油田海区的海洋环境条件,试验研究了不同结构型式潜堤的稳定性和保滩促淤效果,对潜堤的保滩促淤效果和淤积速率进行了预测,对工程布置、潜堤结构方案、基础冲刷防护措施和潜堤顶高程提出了建议．  相似文献   

珠江三角洲地区未来海平面上升及风暴潮增水的耕地损失预测   总被引：1，自引：0，他引：1  

康蕾  马丽  刘毅 《地理学报》2015,70(9):1375-1389

珠江三角洲地区是中国海岸带中风暴潮灾害最集中的区域之一。在全球气候变化和海平面上升的影响下,风暴潮灾害将对该地区农业生产造成巨大的损失。在借鉴相关经验与研究的基础上,建立风暴潮增水灾害耕地产量损失评估模型,选择广东省珠江三角洲地区为研究区域,以该地区的DEM、土地利用等数据为基础,通过实地调研获取当地的作物种植结构、轮作方式、作物单产、不同淹没高度下不同作物的损失率等数据资料,基于未来海平面上升及风暴潮增水的不同时间情景,估算并分析了2030、2050及2100年珠三角地区耕地受灾范围的空间分布特征及产量损失变化情况。结果表明：受气候变化的影响,未来珠三角地区风暴潮影响下的耕地淹没面积比重不断上升,其中阳江、佛山和东莞等地耕地淹没面积从2030年到2100年增加较为明显,广州和珠海的耕地淹没面积增加幅度则较为缓和。从耕地淹没造成的农业产量损失来看,蔬菜、稻谷和花生等主要作物的损失产量比重呈现增加趋势,且蔬菜的增幅最大,其次是稻谷。其中广州、江门、阳江等地稻谷、花生、蔬菜的损失产量比重均表现为持续上升。  相似文献   

基于LabVIEW的自升沉式潜标模拟测试系统设计     

陈宗喜  张喜验  綦声波  郭安刚 《海洋技术学报》2012,31(2):1-5

自升沉式潜标正式布放使用前应进行大量的测试试验工作。为了能够在岸边或实验室对潜标的各项性能进行验证和调试工作,开发了基于LabVIEW的潜标模拟测试系统。该系统充分利用虚拟仪器的特点,采用模块化编程技术,利用软件模拟潜标在水下的各种运动状态及传感器感应的测量参数变化,或通过对现场测量数据的回放查找分析潜标系统本身存在的缺陷,实现潜标不下水或少下水就可以进行全面测试的目的。实验结果表明,利用模拟测试系统可以进行固定值、极值和连续变化值模拟,能够缩短设备开发周期,优化系统控制方案,对提高产品质量具有非常重要的作用。  相似文献