Flow and transport characteristics at an Epinephelus guttatus (red hind grouper) spawning aggregation site in St. Thomas (US Virgin Islands)

This study characterizes the flow field at a spawning site located at the shelf break of a Caribbean island for the Epinephelus guttatus (red hind grouper) in relation to this species spawning events. In order to understand the oceanographic dynamics targeted by the fishes, current measurements were profiled throughout the water column for almost a year at the spawning site. The characteristics of the flow field and its evolution after spawning were investigated by using a numerical ocean model that resolved the observed tide and simulated the island scale flow where passive, neutrally buoyant virtual particles were released for 10 days to trace the flow pathways.Observed currents during the spawning period revealed that the flow was vertically sheared, to the south and weakest at the bottom, and to the west or east at the surface. The tidal analysis revealed that the flow at the time of spawning was directed across and on-shelf, although weaker close to the bottom. The model showed that the initial on-shelf transport was counteracted by the bottom flow directed to the shelf break, where virtual particles were entrained by the downwelling flow. A significant percent of particles resided less than two hundred meters deep, in the vicinity of the chlorophyll maximum and returned to the shelf break, close to the release location within 8-10 days. This journey was largely controlled by the timing between downwelling at the spawning site and upwelling further east at the shelf break, which was driven by the coupling between wind and tide induced vertical movements at the shelf break and deeper. The release location, vertical rotation of its flow field, and its transport properties were shown to be relatively resilient to the passage of transient sub-mesoscale eddies as well as to acute mesoscale flow reversals, suggesting that physical retention is maximized in the area surrounding the spawning site.     

Numerical simulation of benzene transport in shoreline groundwater affected by tides under different conditions

● An approach for assessing the transport of benzene on the beach was proposed. ● The behavior of benzene in the subsurface of the beach was impacted by tide. ● Tidal amplitude influenced the travel speed and the benzene biodegradation. ● Hydraulic conductivity had the impact on plume residence time and biodegradation. ● Plume dispersed and concentration decreased due to high longitudinal dispersivity. The release and transport of benzene in coastal aquifers were investigated in the present study. Numerical simulations were implemented using the SEAM3D, coupled with GMS, to study the behavior of benzene in the subsurface of tidally influenced beaches. The transport and fate of the benzene plume were simulated, considering advection, dispersion, sorption, biodegradation, and dissolution on the beach. Different tide amplitudes, aquifer characteristics, and pollutant release locations were studied. It was found that the tide amplitude, hydraulic conductivity, and longitudinal dispersivity were the primary factors affecting the fate and transport of benzene. The tidal amplitude influenced the transport speed and percentage of biodegradation of benzene plume in the beach. A high tidal range reduced the spreading area and enhanced the rate of benzene biodegradation. Hydraulic conductivity had an impact on plume residence time and the percentage of contaminant biodegradation. Lower hydraulic conductivity induced longer residence time in each beach portion and a higher percentage of biodegradation on the beach. The plume dispersed and the concentration decreased due to high longitudinal dispersivity. The results can be used to support future risk assessment and management for the shorelines impacted by spill and leaking accidents. Modeling the heterogeneous beach aquifer subjected to tides can also be further explored in the future study.     

秦皇岛市海洋生态环境保护与建设探讨

本文通过对秦皇岛市海洋生态环境质量的调查分析,提出了影响生态环境 的主要问题,进而对该海域的生态环境保护与生态建设提出了切实可行的对策。     

潮汐对江水致突变性的影响

对某潮汐河流从下游至上游共设A、B、C、D、E五个采样点,用Ames试验、双微核试验及单细胞凝胶电泳试验(彗星试验)检测涨潮和落潮时江水中有机污染物的致突变性.结果表明,Ames试验各采样点样品都有致突变性,且从上游至下游逐渐增强;对TA98加S9致突变性增加;双微核试验、彗星试验检测出染色体及DNA损伤剂,并以A点作用最强.涨潮时各点致突变强度较落潮时强.     

影响赤潮的气象因素分析

以 1 998年 7～ 1 0月辽东湾海域赤潮为例 ,分析了气象因素对赤潮全过程的影响。分析表明 :气温、降水、光照、风速等气象因素与赤潮的发生、发展和消亡有密切的关系 ,气象条件是诱发赤潮的关键因素。在温度适宜的情况下 ,降水量的多少对赤潮的发生、发展有关键的作用。最后探讨了利用气象因素与赤潮的关系进行赤潮发生、发展的气象潜势预报的基本思路     

考洲洋水环境质量现状及受潮汐影响变化分析

文章应用单因子标准指数法、算术均值多因子指数法和营养状态指数法相结合的方法对当前考洲洋海域海水质量状况进行了评价,并依据考洲洋在潮汐涨、落情况下海水质量的变化,定量分析了考洲洋潮汐对其海水水质的影响。结果表明:磷酸盐、无机氮、石油类是影响考洲洋海域环境质量的主要因子,考洲洋内部海域均处于富营养化状态,总体水质状况为良好以下,潮水的涌入能改善考洲洋的水质状况,涨潮时期各航次的算术均值多因子指数之和比退潮时期平均降低了13.92%。且潮汐的变化对主要污染因子的影响顺序为:无机氮>磷酸盐>石油类,最后提出了考洲洋污染防治的对策和建议。     

横门围垦对邻近海域水环境影响的数值模拟

用二维水动力数值模型,模拟了横门围垦工程对邻近海域水环境的影响。计算结果表明,工程后流速的改变幅度在-10.15～ 10.03cm/s之间,平均为-3.39cm/s。水位的改变幅度在-5.24～ 8.85cm之间,平均为-0.16cm,大潮期间落潮最大流速时水位的变化幅度,稍大于涨潮最大流速时的变化幅度。围垦工程完成后,邻近海域浅滩处的流速进一步降低,有利于促进淤积,加快浅滩成围速度,而深槽处的流速则略有提高,对河道泄洪没有太大影响。邻近海区水位低潮时将略有下降,高潮时将略有上升,但变化不大,最大不超过10cm,平均不到1cm。     

南麂列岛潮间带底栖藻类与环境的关系探讨

根据南麂列岛的国胜岙,大沙岙和上马鞍等３条潮间带的底栖藻类监测结果,结合同区域的水质及底质环境质量,初步评价了该３个区栖藻类的生态种群,密度,形状及季节变化与环境质量之间的关系。     

中国历代灾害性海潮频率特征及时间序列的分形研究

根据中国历代灾害性海潮史料,运用一般统计方法和分形理论对其时间序列进行了分析,不仅探讨了历史灾害性海潮随时间演进的频率变化特征,而且判定了灾害性海潮时间序列的分形性质,在经基础上,还深入讨论了其分维与历代灾害性海潮暴积累发生次数和累积发生频率之间的关系,以及分维随时间演进的变化趋势。     

荧光光谱结合主成分分析对赤潮藻的识别测定

利用主成分分析和非负最小二乘法,建立了我国近海常见的11种赤潮藻在属水平上的活体荧光识别测定技术.利用Delaunay三维插值法,消除浮游藻三维荧光光谱的瑞利散射和拉曼散射峰, 根据Fisher判别分析方法对各主成分及其组合的分辨能力的判别结果,确定赤潮藻三维荧光光谱的第一主成分得分谱和第二主成分得分谱作为赤潮藻识别特征谱,建立赤潮藻荧光特征谱库,在此基础上,利用非负最小二乘法对11种赤潮藻在属水平上进行识别测定,赤潮藻的识别正确率≥85%,其中9种赤潮藻的识别正确率≥90%,特别是对于近几年东海发生赤潮频率极高的东海原甲藻（Prorocentrum donghaiense）、中肋骨条藻（Skeletonema costatum）和裸甲藻（Gymnodinium sp.）,识别正确率≥95%.本研究表明,利用主成分分析提取赤潮藻三维荧光光谱特征以实现赤潮藻在属水平上的识别测定是可行的.