江苏大丰潮滩悬沙级配特征及其动力响应   总被引：1，自引：5，他引：1  

李占海  高抒  沈焕庭  汪亚平 《海洋学报》2006,28(4):87-95

根据2002和2003年夏季在江苏大丰潮滩的现场观测资料,详细分析了悬沙级配的时空分布特征、影响因素及其对再悬浮、沉降和流速的响应.研究结果表明,悬沙颗粒较细,以粉砂为主,悬沙级配在潮周期内的变化模式有两种类型:一是稳定型,悬沙级配的时空(垂向和平面)变化很小;二是双峰型,悬沙级配的时空变化显著,粗细峰高度不断变化.再悬浮、沉降、涨潮时输入潮滩的悬沙和底质级配是影响悬沙级配的重要因子.再悬浮使粗颗粒悬沙的含量增加,悬沙与底质级配不断接近,沉降对悬沙级配的影响与再悬浮相反.再悬浮发生时悬沙级配对流速有明显响应.在没有再悬浮和沉降影响的情况下,潮滩不同部位、不同时间的悬沙级配趋于稳定和相同,对这种状态下的悬沙级配可称为背景悬沙级配,大丰潮滩背景悬沙级配的平均粒径为7μm.  相似文献   

Comparison of Drags on Fish Cages of Different Shapes   总被引：1，自引：0，他引：1  

詹杰民 苏炜李毓湘  贾晓平黄武林 《中国海洋工程》2006,20(3):457-471

1 .Introduction Commercial fishfarming in net cages is becoming widespread around the world as an importantsource of food.In PRChina ,mostfishfarmingtakes placeincalmcoastal areas .Fishcages work wellat these sites becausethe environmental forces are usua…  相似文献   

Estimation of Land Subsidence Based on Groundwater Flow Model   总被引：8，自引：0，他引：8  

Shui-Long Shen  Ye-Shuang Xu  Zhen-Shun Hong 《Marine Georesources & Geotechnology》2006,24(2):149-167

This article presents an approach for estimating land subsidence due to withdrawal of groundwater. The proposed method calculates the groundwater seepage in 3-D-condition and calculates the land subsidence one-dimensionally. The governing equation on groundwater seepage is based on the three-dimensional mass conservation law and the principle of effective stress. The land subsidence calculation method is derived based on the following assumptions: (1) displacements occur only in the vertical direction, and (2) in vertical direction the total stresses do not change. The governing equation is solved by numerical method, i.e., finite element method (FEM) in spatial discretization and finite difference method (FDM) in time series discretization. In FEM Galerkin method is adopted and in FDM, lumped matrix method is employed. The proposed method is calibrated via analyzing 1-D consolidation problem and the results are compared with those from Terzaghi's one-dimensional consolidation theory and oedometer test. The proposed method is employed to analyze the consolidation of a soft layer due to withdrawal of groundwater from an aquifer under it. Moreover, this method is also applied to a field case of land subsidence due to groundwater pumping in a gas production field in Japan. The analytical results are compared with the field observed data. The results show that this approach simulates the field case well.  相似文献   

基于AHP法和灰色模式识别理论的海底管道系统路由定量风险评估   总被引：3，自引：1，他引：3  

徐慧 肖楠郭振邦  王金英 《海洋工程》2005,23(4):105-110

根据海底管道路由潜在风险的特点及风险类型,提出了一种将层次分析法（AHP法）和灰色模式识别理论相结合的海底管道系统路由定量风险评估方法,该方法利用AHP确定风险评价指标体系,运用灰色模式识别理论,建立识别结果标准,并结合实际工程进行计算,计算结果表明该方法是可行的.  相似文献   

中国近海沿岸海温多时间尺度变率及影响其变化的天气气候因素   总被引：3，自引：0，他引：3  

白彬人  宋家喜 《海洋预报》2005,22(4):78-88

本文通过对中国近海13个海洋站1959年～2003年逐日日平均海表温度及其相关数据的处理分析,结合中国近海多年逐日天气实况,研究了中国近海水温的短时（1d）、过程、旬、月、年际变率以及海温的长期趋势变化,并在此基础上详细讨论了影响中国近海各时间尺度水温变化的天气气候因素.  相似文献   

白云凹陷地球物理场及深部结构特征   总被引：13，自引：2，他引：13  

吴湘杰  周蒂  庞雄  郝沪军  申俊 《热带海洋学报》2005,24(2):62-69

珠江口盆地白云凹陷是南海最具代表性的第三系深水陆坡沉积区。以穿过白云凹陷中部的一条深反射地震剖面(14s)为研究基础，采用综合地球物理研究方法分析了该区地球物理场特征，根据重力异常平面等值线勾画了白云凹陷的形态，并提取该测线相对应的重磁剖面数据，利用重磁资料和地震剖面进行了综合反演。以深剖面地震资料建立了地质模型，利用所得的重力数据进行了研究深部结构的正演拟合，实测与计算值拟合较好，支持中生代俯冲洋壳存在的观点；同时结合地震资料对深部结构进行了分析，该区莫霍面由陆向海抬升，呈阶梯状变化，地壳厚度逐渐减薄，具有大陆边缘陆壳向洋壳过渡的特征。根据地质模型还进行了变密度综合反演拟合来分析基底岩性特征，该区基底主要为中酸性岩浆岩，部分为变质岩和基性火山岩，岩石密度由陆向洋逐渐减小，磁性体分布不均。  相似文献   

气相色谱指纹法在海上油污染源鉴别中的应用   总被引：4，自引：0，他引：4  

陈伟琪  张珞平 《海洋科学》2003,27(7):67-70

通过一个具体案例,探讨了气相色谱指纹法在海上油污染源鉴别中的应用。该鉴别方法基于样品的正构烷烃气相色谱指纹分析,选择既能表征油种固有特性,又受风化影响较小的正十七烷(n-C17)、正十八烷(n-C18)、姥鲛烷(phy)、植烷(phy)和正二十烷(n-C20)等特征烷烃作为判据,可信度大,而且整个操作流程短(一般不超过半天),较简便易行。  相似文献   

Factors affecting spatial and temporal variability in material exchange between the Southern Everglades wetlands and Florida Bay (USA)     

Martha A. Sutula  Brian C. Perez  Enrique Reyes  Daniel L. Childers  Steve Davis  John W. Day  Jr.  David Rudnick  Fred Sklar 《Estuarine, Coastal and Shelf Science》2003,57(5-6):757-781

Physical and biological processes controlling spatial and temporal variations in material concentration and exchange between the Southern Everglades wetlands and Florida Bay were studied for 2.5 years in three of the five major creek systems draining the watershed. Daily total nitrogen (TN), and total phosphorus (TP) fluxes were measured for 2 years in Taylor River, and ten 10-day intensive studies were conducted in this creek to estimate the seasonal flux of dissolved inorganic nitrogen (N), phosphorus (P), total organic carbon (TOC), and suspended matter. Four 10-day studies were conducted simultaneously in Taylor, McCormick, and Trout Creeks to study the spatial variation in concentration and flux. The annual fluxes of TOC, TN, and TP from the Southern Everglades were estimated from regression equations. The Southern Everglades watershed, a 460-km² area that includes Taylor Slough and the area south of the C-111 canal, exported 7.1 g C m⁻², 0.46 g N m⁻², and 0.007 g P m⁻², annually. Everglades P flux is three to four orders of magnitude lower than published flux estimates from wetlands influenced by terrigenous sedimentary inputs. These low P flux values reflect both the inherently low P content of Everglades surface water and the efficiency of Everglades carbonate sediments and biota in conserving and recycling this limiting nutrient. The seasonal variation of freshwater input to the watershed was responsible for major temporal variations in N, P, and C export to Florida Bay; approximately 99% of the export occurred during the rainy season. Wind-driven forcing was most important during the later stages of the dry season when low freshwater head coincided with southerly winds, resulting in a net import of water and materials into the wetlands. We also observed an east to west decrease in TN:TP ratio from 212:1 to 127:1. Major spatial gradients in N:P ratios and nutrient concentration and flux among the creek were consistent with the westward decrease in surface water runoff from the P-limited Everglades and increased advection of relatively P-rich Gulf of Mexico (GOM) waters into Florida Bay. Comparison of measured nutrient flux from Everglades surface water inputs from this study with published estimates of other sources of nutrients to Florida Bay (i.e. atmospheric deposition, anthropogenic inputs from the Florida Keys, advection from the GOM) show that Everglades runoff represents only 2% of N inputs and 0.5% of P input to Florida Bay.  相似文献   

Large-scale environmental influences on the benthic macroinfauna of the southern Gulf of Mexico     

Hector A. Hernndez-Arana  Ashley A. Rowden  Martin J. Attrill  Richard M. Warwick  Gerardo Gold-Bouchot 《Estuarine, Coastal and Shelf Science》2003,58(4):825-841

The influence of large-scale natural disturbance from winter storms (‘northers’) and river runoff on the macrobenthic community structure of the southern Gulf of Mexico was investigated in both carbonate and transitional carbonate–terrigenous sedimentary environments. Samples of the infauna were obtained in three seasons from 13 stations from two 250 km transects along 80–170 and 20–50 m water depth. Samples after the northers season had the lowest total number of families and individuals, 114 and 2940, respectively, compared to the dry and rainy seasons with 129 and 132 families and 11580 and 15266 individuals, respectively. Spatial patterns of macroinfauna composition varied across and along the shelf as a response to sedimentary environments and depth. Coarser sediments from the carbonate area harboured the highest mean densities per station with 500–24,000 individuals m⁻² and 108–122 families in total, compared to the transitional sediment with 500–8200 individuals m⁻² and 56–74 families across the three seasons. Univariate and multivariate statistical techniques demonstrated that low densities and number of taxa were associated with winter storms, but storm influence was dependent on depth and sediment type. Multiple linear regression analysis and BIOENV analysis indicated that sediment mean grain size, percentage of clay and organic matter best explained the macroinfauna spatial patterns, although BIOENV indicated that depth has an overriding role. An increase in densities of opportunistic taxa (numerous polychaetes of small sizes) was observed four months after the ‘northers’ and this was more evident in the area of carbonate sediment. Additionally a combined disturbance from northers and river runoff is suspected to be responsible for a naturally impoverished macroinfauna community in the transitional sedimentary environment.  相似文献   

盐度和昼夜节律对菲律宾蛤仔摄食率的影响   总被引：16，自引：0，他引：16  

吴桂汉  陈品健  江瑞胜  杨圣云  沈锦兰 《台湾海峡》2002,21(1):72-77

在实验室条件下，用流水系统测定盐度和昼夜节律对菲律宾蛤仔摄食率的影响。分别对15、20、25、30、35这5个盐度梯度，以及连续24h的00：00、04：00、08：00、12：00、16：00、20：00这6个时间点下菲律宾蛤仔的摄食率进行了测定。结果表明：在15-25的盐度范围内，蛤仔的摄食率随着盐度的升高而增大，在盐度25时达到最大，而在25-35盐度范围内随盐度的增加而减小；在一个昼夜里，蛤仔的摄食率存在显著的差异，夜间的摄食率明显高于白昼，00：00和12：00分别是两个极值；菲律宾蛤仔是一个有着明显昼夜节律性的底栖动物，并且对盐度有一个适应范围，盐度25-30是其最适的盐度。本实验为以后进一步研究菲律宾蛤仔在贝类混养虾池中的作用奠定了基础。  相似文献