基于ECOMSED模式的兴化湾三维潮流泥沙数值模拟研究

通过三维ECOMSED模式,对兴化湾内的泥沙变化规律进行了分析论证。模拟结果与实测值的对比分析表明,模拟结果较好,可以较准确地描述兴化湾的潮流泥沙特征。分析发现,兴化湾大部分海域的含沙量很低,兴化湾内普遍呈现冲淤稳定的状态,海区的冲淤变化量维持在1个较小的水平,淤积主要集中在近岸浅滩区域,近岸年淤积变化量普遍呈增大趋势。

基于SWAN和ECOMSED模式的大风作用下黄骅港波浪、潮流、泥沙的三维数值模拟

根据黄骅港外航道淤积问题的具体情况,本文采用三维细颗粒泥沙的ECOMSED模式对黄骅港海域的潮流、泥沙进行了模拟。数值计算结果与潮流为主要动力条件的现场实测结果进行了比较,二者吻合较好。在此基础上,本文采用SWAN风浪模型和ECOMSED对黄骅港骤淤进行了数值模拟,并与收集到的现场实测资料进行比较,也得到较好的结果。数值模拟显示,波浪是造成黄骅港外航道泥沙淤积的主要动力因素;在以波浪为主的动力条件下,含沙量在波浪破碎带达到最大,并且沿水深变化梯度较大。破碎带当地的泥沙跨过航道落淤是黄骅港外航道淤积的主要原因,岸边泥沙随落潮流下泻不是黄骅港外航道大风骤淤的主要原因。

ECOMSED数学模型研究悬浮物对海洋环境影响

文章利用ECOMSED三维水动力数学模型,对莱州海事工作船码头工程海域潮流进行数值模拟,在潮流模拟验证确的基础上,建立了悬浮物输移、扩散预测模型,预测了在工程基槽开挖、航道和港池疏浚施工过程中引起的悬浮物浓度,给出了悬浮物超标的面积等,从而分析了该扩建工程对海洋水质环境的影响。

ECOMSED三维悬沙扩散数值模型在凤城港航道清淤工程建设中的应用

文章用ECOMSED三维近岸水动力泥沙数学模型对山东烟台凤城港附近海区的潮流场进行了较高分辨率数值模拟,在此基础上进一步建立了凤城港航道清淤工程过程中三维悬沙输运-扩散数学模型。该模型以航道中心为悬沙线源,根据工程过程中连续开挖的特点较好的引入泥沙输入源强,准确地模拟了该航道中连续开挖36小时,工程区域及其周围海域表、中和底层泥沙浓度分布特征及其随时间的变化规律。

ECOMSED模式在厦门湾海域潮流场模拟中的应用

本研究基于ECOMSED模式,引入变边界技术,建立厦门湾三维动边界潮流模型,以模拟具有大面积滩涂的厦门湾水动力过程。模型综合考虑九龙江上游径流和M2,S2,N2,K1,P1,O1等6个主要分潮的作用,对整个厦门湾及其毗邻海域进行了一个多月的模拟,最后将模拟结果与实际观测资料进行对比验证,结果表明本研究所建立的模型可以较好地反映厦门湾海域的潮流运动过程,为进一步研究河口海湾地区提供了可靠的技术基础。

基于ECOMSED模型的湛江湾水道三维潮流数值模拟

采用半隐式的ECOMSED(Estuarine,Coastal and Ocean Modeling System with Sediments)三维海洋紊流模式,建立湛江湾湾顶水道的三维潮流数值模型。模型的水平方向采用加密的正交网格以贴合岸线边界,垂向上采用σ坐标以更好地拟合海底地形。通过验证,模拟结果与实测数据符合良好,表明运用该模型可以较好地预报湛江湾的潮流动力特性。为进一步研究湛江湾水道附近水域的温盐变化、泥沙输运提供技术支持。

ECOMSED模型在潮汐水域电厂温排水计算中的应用

以罗源湾内可门电厂取排水工程为例,利用ECOMSED海洋水动力模型,对其水域潮流场和温度场进行了三维数值模拟,模型计算得到的潮位、潮流和温升范围均与电厂运行期间的原体观测资料吻合良好。在此基础上,对电厂已建工程不利工况下温排水的水力热力特性进行了模拟计算,获得了其温升影响范围、垂向温升分布及取水温升。计算结果表明,ECOMSED模型可应用于电厂近区温升预测,能体现冷热水的分层现象。

基于ECOMSED的非恒定流水域盐水入侵数值模拟

为了研究非恒定流水域盐水入侵后的水流特性,利用ECOMSED三维海洋水动力模型,对该水域的潮流场和盐度场进行了三维数值模拟。模拟结果显示:在水槽弯曲处靠近主流线一侧盐度较高;靠近河口处的盐度纵向变化受潮差影响较大;底层咸水入侵的最远距离远大于表层;盐水分层现象在小潮时相对更为明显。该数学模型基本反映了非恒定流水域的盐水入侵特性,并可用于进一步分析盐分输移的机理以及预测盐度的分布情况。

ECOMSED模型动边界处理技术研究

在ECOMSED数值模式的水动力模块基础上,引入了动边界处理技术,建立了数值试验,并采用单一斜坡地形和圆形浅滩斜坡地形对该技术进行了验证。数值试验结果显示,改进后的水动力计算模式可成功再现由涨落潮引起的潮间带漫滩现象,而且模拟得到的水面线较为光滑,且未产生零水深和负水深。

Numerical Simulation of Water Level Under Interaction Between Runoff and Estuarine Dynamics in Tidal Reach of the Yangtze River

The Yangtze Estuary, the largest estuary in China, is under an obvious interaction between runoff and astronomical tide. The research on the interaction is very important for the exploitation and utilization of water resources in this area. A horizontal 2D hydrodynamic numerical model is established and verified in the present study with the modeling rmage from Datong to the Yangtze Estuary. Based on the comparison of high water levels under the interaction between different runoff and estuarine dynamics, some conclusions are drawn. By revealing the general laws about the relationship between the astronomical tide and flood, the flood level is forecasted to lay a foundation for further research on storm surge in the Yangtze Estuary.

Insights into community-based bioassessment of environmental quality status using microphytobenthos in estuarine intertidal ecosystems

The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos（MPB） in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during a 1-year cycle（September 2006-August 2007） at four sampling stations in the Nakdong River Estuary,Korea.Environmental variables,such as salinity,radiation,grain size of sediment,Si（OH）4（Si）,nitrate（NO3^-）,nitrite（NO2^-）,ammonium（NH4~＋） and phosphates（PO4^（3-））,were measured synchronously for comparison with biotic parameters.The statistical analyses were carried out for assessment the relationship between biotic and environmental parameters.The results showed that：（1） the MPB community structures were significant differences among four sampling stations;（2） spatial variation in the MPB communities were significantly correlated with environmental variables,especially the nutrient NH4＋ in combination with salinity and grain size;（3） three species（Navicula lacustris,Pleurosigma anglulatum and Fragilaria sp.1） were significantly correlated with nutrients and/or Si;and（4） the species richness and diversity were significantly correlated with the grain size.It is suggested that MPB communities may be used as a potentially robust bioindicator for assessing environmental quality status in estuarine intertidal ecosystems.

Late Quaternary diatom and sea level changes in estuarine plain of the Jiulong River

Four units and twenty-four zones of diatom have been discerned in the Borehole ZK5 in the estuarine plain of the Jiulong River, Fujian Province. Comprehensive analysis of these, together with microbiological assemblages and age determinations in some other boreholes, shows that during the Late Wurm Glacial, sea level of the study area rose and fell frequently, but had principally been in the environments of estuary-bay. This mainly resulted from the tectonic subouction. In this period 3 low sea levels occurred. at 18, 16 and 12 kaBP respectively. During Holocene, sea weter intruded massively and the sea level over the transgnaion maximum had been 5-10 m higher than that of the present.

Partitioning of grain-size components of estuarine sediments and implications for sediment transport in southwestern Laizhou Bay, China

Sediment transport in estuarine systems has been of increasing interest for scientists during the past few decades. However, the mechanisms for sediment redistribution remain unclear. We characterized in detail sediment transport in the Xiaoqing River estuary using the mathematical Weibull function to partition grain-size components of surface sediments in the southwestern Laizhou Bay, Northeast China. Four partitioned components: finer than 4,4.6-12.5, 23.4-63.3, and 67.1-132.6 μm were interpreted in terms of hydrodynamic conditions. During sediment transport, silt grains were suspended and moved seaward from three depositional centers, whereas fine-grained sands moved generally landward. Overall, sediments are transported clockwise in a generally NNE direction near shore and then turn eastward offshore. The mathematical partitioning method showed a great potential for future estuarine environmental studies.

ENVIRONMENTAL CHANGES SINCE LATE PLEISTOCENE IN ESTUARINE PLAIN OF JIULONG RIVER, FUJIAN PROVINCE

Based on the evidences of lithostratigraphy, palynology, micropaleontolopy and geochronology, paleoenvironments since the Late Pleistocene in the study area have been reconstructed. One of the most important inferences is that two marine transgressions have occurred, one in Wurm Sub-interglacial and the other Postglacial. The former had caused the study area to be in an estuary-bay envirment over the transgression maximum, with a sea level of no less than 10 m below present; foe latter reached its maximum over the Atlantic stage, with sedimentary environments of estuary-bay, hay or shallow sea, and the sea level arrived at the highest elevation in about 6 - 5 ka B.P. Furthermore, it is notable that, during the Late Wurm Glacial, the study area area had principally been in an estuary-bay environment, although the climate, like many other areas, turned cold and dry, It reflects a general trend of crustal subduction in Jiulong Estudrine Plain over this pened.

An integrated measurement and modeling methodology for estuarine water quality management

This paper describes research undertaken by the authors to develop an integrated measurement and modeling methodology for water quality management of estuaries. The approach developed utilizes modeling and measurement results in a synergistic manner. Modeling results were initially used to inform the field campaign of appropriate sampling locations and times, and field data were used to develop accurate models. Remote sensing techniques were used to capture data for both model development and model validation. Field surveys were undertaken to provide model initial conditions through data assimilation and determine nutrient fluxes into the model domain. From field data, salinity re- lationships were developed with various water quality parameters, and relationships between chlorophyll a concentrations, transparency, and light attenuation were also developed. These relationships proved to be invaluable in model development, particularly in modeling the growth and decay of chlorophyll a. Cork Harbour, an estuary that regularly experiences summer algal blooms due to anthropogenic sources of nutrients, was used as a case study to develop the methodology. The integration of remote sensing, conventional fieldwork, and modeling is one of the novel aspects of this research and the approach developed has widespread applicability.

Approach of moving boundary and its application in 3D tidal current simulation of Changjiang (Yangtze) River Estuary based on ECOMSED model

Considering three-dimensional model ECOMSED can not simulate wetting-drying of shoal with its fixed boundary, an approach to represent moving boundary in the model is introduced here. This approach smoothly joints the internal and external mode by making use of wetting and drying technique and is verified by a numerical test which presents a good agreement with the previous test results obtained by other researchers. A three dimensional numerical model is established to simulate the hydrodynamics in spring tide in the Changjiang （Yangtze） River estuary by this modified ECOMSED model which is also validated through the observed field data, the simulation presents a good periodic tidal change. It also successfully simulates the tidal current of computational areas and reproduces the tidal flat intermittent appearance.

Effects of sampling strategies and DNA extraction methods on eDNA metabarcoding: A case study of estuarine fish diversity monitoring

Environmental DNA(eDNA)integrated with metabarcoding is a promising and powerful tool for species composition and biodiversity assessment in aquatic ecosystems and is increasingly applied to evaluate fish diversity.To date,however,no standardized eDNA-based protocol has been established to monitor fish diversity.In this study,we investigated and compared two filtration methods and three DNA extraction methods using three filtration water volumes to determine a suitable approach for eDNA-based fish diversity monitoring in the Pearl River Estuary(PRE),a highly anthropogenically disturbed estuarine ecosystem.Compared to filtration-based precipitation,direct filtration was a more suitable method for eDNA metabarcoding in the PRE.The combined use of DNeasy Blood and Tissue Kit(BT)and traditional phenol/chloroform(PC)extraction produced higher DNA yields,amplicon sequence variants(ASVs),and Shannon diversity indices,and generated more homogeneous and consistent community composition among replicates.Compared to the other combined protocols,the PC and BT methods obtained better species detection,higher fish diversity,and greater consistency for the filtration water volumes of 1000 and 2000 mL,respectively.All eDNA metabarcoding protocols were more sensitive than bottom trawling in the PRE fish surveys and combining two techniques yielded greater taxonomic diversity.Furthermore,combining traditional methods with eDNA analysis enhanced accuracy.These results indicate that methodological decisions related to eDNA metabarcoding should be made with caution for fish community monitoring in estuarine ecosystems.

Interdecadal variability in ecosystem health of Changjiang (Yangtze) River estuary using estuarine biotic integrity index

Ichthyoplankton samples were collected from Changjiang(Yangtze)River estuary in May 2016.Species composition was studied by DNA barcoding and morphological identification.To make better use of the estuarine biotic integrity index(EBI)to assess the ecosystem health of the Changjiang River estuary over the past 30 years,we collected the data of a spring ichthyoplankton survey in the estuary from 1986 to 2016.The EBI was calculated using 12 evaluation metrics,namely,the number of total ichthyoplankton species,estuarine spawning species,estuarine nursery species,estuarine resident species,benthic species,pelagic species,and intolerant species,and the percentages of tolerant species,omnivores,insectivores,carnivores,and natural hybrid species.EBI was calculated in spring in four periods(1986,1999,2007,and 2016)by assigning points of 1,3 or 5,giving values of 50,38,36,and 32,respectively,corresponding to“Good”,“Fair-Poor”,“Fair-Poor”,and“Poor”EBI levels,respectively.Changes in species composition were the primary reason for the significant decreases in EBI between 1986 and 1999,and for the large differences between 1986 and 2007 and between 2007 and 2016.The changes in species composition were influenced by declines in ichthyoplankton species,pollution sensitive species,estuarine nursery species and estuarine sedentary species,and an increase in pollution resistant species.An analysis of EBI interdecadal variability showed that the health status of the Changjiang River estuary ecosystem over the last 30 years first declined and then stabilized at a lower level.This result further settled the argument for urgent protection and restoration of the Changjiang River estuary.

Optimization of Sample Pretreatment for Determination of Polycyclic Aromatic Hydrocarbons in Estuarine Sediments by Gas Chromatography

This study examined levels of polycyclic aromatic hydrocarbons (PAHs) in estuarine sediments in Licun (Qingdao, China) by gas chromatography under optimized conditions for sample pretreatment via ultrasonic extraction, column chromatography, and thin layer chromatography. Methanol and dichloromethane (DCM)/methanol (2:1, v/v) were used in ultrasonic extraction, and DCM was used as eluate for column chromatography. The developing system consisted of n-hexane and DCM at a ratio of 9:1 (v/v), with DCM as the extraction solvent for PAHs-containing silica gel scraped off the plate. When the spiking level is 100 ng, total recoveries of spiked matrices for four target PAHs (phenanthrene, anthracene, pyrene and chrysene) were 83.7%, 76.4%, 85.8%, and 88.7%, respectively, with relative standard deviation (RSD) between 5.0% and 6.5% (n = 4). When the spiking level is 1000 ng, associated total recoveries were 78.6%, 72.7%, 82.7% and 85.3%, respectively, with RSD between 4.4% and 5.3% (n = 4). The opti-mized method was advantageous for determination of PAHs in complex matrix due to its effective sample purification.

基于ECOMSED模型的大亚湾波浪模拟

本文借助ECOMSED模型中的波浪模块(WAVE MODULE)对大亚湾部分海域波浪分布情况进行了数学模拟。用Matlab编写程序对ECOMSED输出数据进行了处理并绘图,得出了计算区域内波浪的分布情况,并对所得结果进行了简要分析。