Numerical Simulation of Nutrient and Phytoplankton Dynamics in Guangxi Coastal Bays,China

The increasing riverine pollutants have resulted in nutrient enrichment and deterioration of water quality in the coastal water of Guangxi Province, China. However, the quantitative relationship between nutrient loads and water quality responses, which is crucial for developing eutrophication control strategies, is not well studied. In this study, the riverine fluxes of nutrients were quan- tified and integrated with nutrient cycling and phytoplankton dynamics by using box models for Guangxi coastal bays. The model concepts and biogeochemical equations were the same; while most model parameters were specific for each bay. The parameters were calibrated with seasonal observations during 2006--2007, and validated with yearly averaged measurements in 2009. The gen-eral features of nutrient and phytoplankton dynamics were reproduced, and the models were proved feasible under a wide range of bay conditions. Dissolved inorganic nitrogen was depleted during the spring algal bloom in Zhenzhu Bay and Fangcheng Bay with relatively less nutrient inputs. Phosphorus concentration was high in spring, which decreased then due to continuous phytoplankton consumption. Chlorophyll-a concentration reached its annual maximum in summer, but was the minimum in winter. Eutrophication was characterized by both an increase in nutrient concentrations and phytoplankton biomass in Lianzhou Bay. Either about 80% re-duction of nitrogen or 70% reduction of phosphorus was required to control the algal bloom in Lianzhou Bay. Defects of the models were discussed and suggestions to the environmental protection of Guangxi coastal bays were proposed.     

Diagnosis of physical and biological control over phytoplankton in the Gulf of Maine-Georges Bank region using an adjoint data assimilation approach

The linkage between physical and biological processes, particularly the effect of the circulation field on the distribution of phytoplankton, is studied by applying a two-dimensional model and an adjoint data assimilation approach to the Gulf of Maine-Georges Bank region. The model results, comparing well with observation data, reveal seasonal and geographic variations of phytoplankton concentration and verify that the seasonal cycles of phytoplankton are controlled by both biological sources and ad-vection processes which are functions of space and time and counterbalance each other. Although advective flux divergences have greater magnitudes on Georges Bank than in the coastal region of the western Gulf of Maine, advection control over phytoplankton concentration is more significant in the coastal region of the western Gulf of Maine. The model results also suggest that the two separated populations in the coastal regions of the western Gulf of Maine and on Georges Bank are self-sustaining.     

1975—2020年烟台芝罘湾海湾形态变化及驱动因素

海湾是海岸带综合开发利用的主要场所,研究海湾形态变化及驱动因素,可为海湾的开发利用与保护修复提供科学依据。以烟台芝罘湾为研究区域,基于Landsat遥感影像提取1975—2020年10个时相的海湾空间信息,进而从海湾岸线开发利用程度、海湾面积、形状、重心分布4个方面分析海湾形态变化时空特征及驱动因素。结果表明,1975年以来,研究区海湾的形态变化显著且复杂,主要体现为：海湾岸线的开发利用程度持续增强,岸线呈背陆向海移动;海湾面积逐渐萎缩,45年来减少了25.99%,主要集中在1975—2000年;海湾形状指数由1.33增加至2.23,海湾形状总体趋向复杂;海湾重心位置背陆向海迁移,重心整体向海位移647.79 m。总体而言,填海造地建设港口码头和近岸围海养殖是导致海湾形态发生变化的主要原因。     

海湾围填海强度指数的应用

围填海强度指数RII（reclamation intensity index）为海湾围填海面积占海湾总面积的比率,用以反映海湾利用海域围海造地的开发强度．本研究引用福建省海湾数模与环境研究对海湾围填海综合评价成果的数据,以湄洲湾的围填海方案为例讨论海湾围填海对环境影响的累积效应,通过福建主要海湾的RII与综合评价指数的相关性分析,提出RII可作为海湾围填海的限制性指标,应用于海湾围填海的影响评价和围填海规模的控制．     

行摄菲律宾

进入11月,中国北方的气温陡然降低,瑟瑟的秋风将变黄的树叶吹落在街道上的每个角落,最终化泥作尘。最北的漠河地区已然冰天雪地,一片肃然。而此时却正是东南亚国家旅游旺季的开始。马尼拉和迷人的海湾落日菲律宾的首都马尼拉,在我看来是一个"纠结"的城市——它拥有大都市的繁华,广厦林立、商铺如云,豪车美女穿梭于灯红酒绿与富丽堂皇,而低矮     

靖海湾表层沉积物粒度特征及沉积动力环境分区

随着人类开发活动的加剧,靖海湾沉积动力环境受到显著影响。靖海湾57个站位的表层沉积物调查资料的分析结果表明,靖海湾表层沉积物以砂质粉砂和粉砂为主,含有少量泥,沉积物粒径偏小;随着水动力条件的增强,表层沉积物平均粒径增大,分选系数呈增大趋势,正偏更显著;以此为依据,利用Pejrup三角图式把靖海湾划分出4个沉积动力环境单元,结合粒度概率图,认为靖海湾沉积物搬运方式以悬浮为主,跃移次之,并有少量以推移方式搬运,随着水动力条件的增强,悬浮组分减少,跃移组分和推移组分增加。     

福建东山湾潮流和余流特征研究

东山湾位于台湾海峡南口的西岸,属于潮控型半封闭海湾.本文章通过对M1站1周年的流速、流向及对应的风速、风向资料进行分析,结果表明:M1站正压流动特征显著,潮流日不等现象较明显,相邻潮次中涨急流速明显小于落急流速.观测期间,M1表、中、底3层实测最大涨潮流速分别为83,78,71 cm/s,实测最大落潮流速分别为152,104,100 cm/s.夏季表层余流流速明显大于中层和底层,冬季各层余流速相差则较小.径流是M1站的余流的主要因子.夏季,径流对表层作用最为明显,其余流流速明显大于中层和底层,中、底层由于受温盐跃层产生的斜压效应作用,出现较长时段的北向余流;冬季东山湾平面和垂向温、盐分布均匀,各层余流流向均为落潮方向,且表层往底层方向,流速变幅不大.由于其半封闭型的海湾形态,风应力对东山湾的余流贡献较小.     

福建罗源湾海湾生态系统脆弱性评价

本研究以"暴露程度-敏感性-适应能力"为框架,构建了罗源湾海湾生态系统脆弱性评价指标体系,并运用模糊综合评价法对罗源湾海湾生态系统在1986~1990、2004~2006、2010~2012年三个阶段的脆弱性状况开展了定量评价,结果显示,罗源湾海湾生态系统在三个阶段均处于"中度脆弱"水平,综合评价得分逐年上升,呈现渐脆弱趋势.三个子系统的模糊评价结果表明,罗源湾海湾生态系统面临的暴露程度不断增大,其主要人为胁迫因子为滩涂围垦面积、临港工业发展和海水养殖密度;其次,罗源湾海湾生态系统的敏感性也越来越强,主要的敏感因子有海洋生物质量综合指数、浮游动物和潮间带底栖生物多样性指数和鱼卵仔稚鱼种类与密度;与此同时,适应能力则呈较好态势.研究结果可为相似区域海湾生态系统脆弱性评价提供参考.     

海湾水环境影响的约瑟夫-新德那模式预测

对应用约瑟夫-新德那模式进行海湾水环境影响预测中存在的问题作了初步分析,海域水流、混合深度值的选取及特殊污染物的存在等是影响预测结果准确性的主要因素。潮流憩流状态时,污染物的迁移扩散主要取决于污染物的混合速度,污染物基本上以近似于半圆形呈π弧度的角度向水体混合扩散,预测结果与污染物实际迁移扩散状况大致吻合;潮流非憩流或大部分时间为非憩流状态时,海域水流对污染物的迁移扩散影响较大,混合角度与海流流速成反比,污染物向水体扩散的实际混合角度要小于π弧度,预测的结果与污染物实际迁移扩散状况存在较大差距。海域水流对污染物迁移距离产生很大影响,水流愈大,污染物迁移的距离就愈远。混合深度的取值也直接关系到预测结果的准确性,若按可能受影响范围海域的平均水深值作为混合深度取值,其预测结果要比水深取2m时的预测结果更接近真实状况。对已达标排放的废水进行影响预测时,结果与实际情况接近,而对高浓度石油类的废水含量的影响预测却与实际情况差异极大。     

河网海湾水动力联网数学模型

在一维显式、二维隐式水动力联网数学模型的基础上,建立了一种一维、二维全隐河网海湾水动力联网数学模型。该一维河网模型采用Preissmann四点隐式格式,用节点水位控制法进行数值计算,二维海湾模型采用改进型双向隐式(DSI)法进行数值求解。在河口一维、二维连接处,水力因子通过接口断面法传递,无需重叠一个一维河段来传递水力因子,避免了口门处二维网格需取较小尺度的问题。模型在珠江三角洲河网及横门、洪奇沥口门海域做了检验,验证结果表明,建立的河网海湾水动力联网数学模型是可行的,可以用于河网、河口治理工程的数值研究。