Simulating the influence of various nutrient sources on hypoxia off the Changjiang River Estuary

Hypoxia is increasingly reported off the Changjiang River Estuary with the confluence of multiple high volume nutrient sources. The Regional Ocean Modeling System coupled with a biological model was used to analyze the effect of different nutrient sources on the development of hypoxia off the Changjiang River Estuary. By comparing to observed data, our model suitably captured the regional dynamics of chlorophyll a, dissolved oxygen, and nutrient concentration. A series of sensitivity experiments were conducted to investigate the hypoxia response to the various nutrient sources, such as loading from the Changjiang River, Kuroshio and Taiwan Warm Current. Our model results indicated that nutrients from different sources significantly influenced the hypoxia off the Changjiang River Estuary, and it was mostly affected by nutrients sourced from the Kuroshio. The nutrients input from the Changjiang River had larger impacts on the hypoxia in the north of 30°N than that in the south of 30°N. The nutrients sourced from the Taiwan Strait had a least influence on the hypoxia off the Changjiang River Estuary.     

Characterization of marine microplankton communities of Qingdao coastal areas using randomly amplified polymorphic DNA（RAPD）

Microplankton communities of three coastal sites of Qingdao, Shandong Province, China were investigated using RAPD (random amplified polymorphic DNA) molecular markers and morphological observations. Eight RAPD-primers were selected to amplify the DNA polymorphy. The genetic distances inferred from the pairwise similari-ties were calculated for the phylogenetic tree construction. Meantime, the traditional microscopic determination, a way of visualizing the species composition, was performed to detect the major taxa of microplanktons from all samples. Results showed that: (1) the band sharing index values were in the range of 0. 504 2-0. 763 2 among samples from the same sampling site at different time scales, while 0.406 5-0.685 7 among the samples from different stations at the same time scales, indicating that spatial variations of microplankton communities were more pronounced than temporal ones; (2) samples from the same station basically clustered together, cor-responding to the geographic distribution of the sampling sites; (3) diversity derived from genetic and morpho-logical data did not correspond with each other well.     

Seasonal and spatial distributions of phytoplankton biomass associated with monsoon and oceanic environments in the South China Sea

Seasonal variations of phytoplankton/chlorophyll-a （Chl-a） distribution, sea surface wind, sea height anomaly, sea surface temperature and other oceanic environments for long periods are analyzed in the South China Sea （SCS）, especially in the two typical regions off the east coast of Vietnam and off the northwest coast of Luzon, using remote sensing data and other oceanographic data. The results show that seasonal and spatial distributions of phytoplankton biomass in the SCS are primarily influenced by the monsoon winds and oceanic environments. Off the east coast of Vietnam, Chl-a concentration is a peak in August, a jet shape extending into the interior SCS, which is associated with strong southwesterly monsoon winds, the coastal upwetling induced by offshore Ekman transport and the strong offshore current in the western SCS. In December, high Chl-a concentration appears in the upwelling region off the northwest coast of Luzon and spreads southwestward. Strong mixing by the strong northeasterly monsoon winds, the cyclonic circulation, southwestward coastal currents and river discharge have impacts on distribution of phytoplankton, so that the high phytoplankton biomass extends from the coastal areas over the northern SCS to the entire SCS in winter. These research activities could be important for revealing spatial and temporal patterns of phytoplankton and their interactions with physical environments in the SCS.     

莱州湾沉积物粒度与重金属分布特征

作者依据2019年8月份莱州湾海洋沉积物调查资料,分析了该海域表层沉积物粒径组成、重金属时空分布特征并评价了其生态风险。结果显示,莱州湾沉积物分为砂质粉砂、粉砂、粉砂质砂和砂4种类型,以砂质粉砂为主,其次为粉砂与粉砂质砂,再次为砂,中值粒径平均58.956μm;表层沉积物中Cr、Zn、Pb、Cu、As、Cd、Hg和TOC平均含量分别为57.6、52.6、18.7、15.3、9.14、0.130、0.0234 mg/kg和0.222%;由于河流排海物质和莱州湾内潮流运动,导致Cu、Pb、Zn、As、Cr和Cd基本呈现中部海域含量较高,西部海域高于东部海域的特征,东南部海域Cd、Hg与矿产资源的开发相关;14.3%的站位综合潜在生态风险属于中生态风险,Cd对综合潜在生态风险指数的贡献率最高,为主要潜在生态风险因子;研究区域中重金属Cu、Zn含量的分布与沉积物粒径和有机碳的含量密切相关。     

基于双隐层ANN模型的叶绿素a浓度智能预报方法

利用2019年5月WZ02生态浮标监测数据,建立了两种不同隐层人工神经网络(ANN)模型的叶绿素a(Chl-a)智能预报方法,并对单隐层和双隐层模型的预测结果做了对比.结果表明:双隐层结构预测结果精度更高,泛化能力更强,一定程度上说明了深层学习比浅层学习对信息的主要特征提取能力更有优势.同时,对数据样本集合进行了系统预...     

2011年辽宁东港赤潮监控区浮游植物群落结构特征

研究了辽宁东港鸭绿江口海域赤潮监控区6个测站的浮游植物种类组成、数量分布和群落结构特征.2011年5-10月浮游植物数量变化范围为9.80伊104~3.66伊108个/m3,浮游植物数量高峰出现在春季5月,最低值出现在夏季8月.共发现浮游植物4门33属70种,其中硅藻27属57种,甲藻4属11种,黄藻 1 属 1种,金藻 1 属 1种.优势种为尖刺拟菱形藻(Pseudo-nitzschia pungens)、中肋骨条藻(Skeletonema costatum)、窄隙角毛藻(Chaetoceros affinis)和夜光藻(Noctiluca scintillans),均为赤潮生物种.春季5月多样性指数和均匀度指数较低,但优势度指数较高,优势种是尖刺拟菱形藻,成为形成赤潮的潜在生物要素.     

海月水母(Aurelia sp.1)对中肋骨条藻(Skeletonema costatum)和东海原甲藻(Prorocentrum donghaiense)摄食的研究

采用饵料浓度差减法,在实验条件下研究了不同细胞密度的中肋骨条藻和东海原甲藻对海月水母水螅体、碟状体和水母体摄食活动的影响。结果表明,不同种类和密度的微藻细胞密度对水螅体、碟状体和水母体的摄食有显著影响。在实验的藻细胞密度范围内,随藻细胞密度的增加,水螅体和碟状体对中肋骨条藻和东海原甲藻的摄食率一直升高。水螅体对中肋骨条藻和东海原甲藻的最大摄食率均发生在藻细胞密度最高处,分别为4623cells/(ind.h)和4118cells/(ind.h)。碟状体对中肋骨条藻和东海原甲藻的最大摄食率也是发生在藻细胞密度最高处,分别为174671cells/(ind.h)和47218cells/(ind.h)。清滤率随着藻细胞密度增加而降低。在相似细胞密度下,碟状体对中肋骨条藻的摄食率高于东海原甲藻。水螅体和碟状体对同种藻的摄食情况不同,在相似藻细胞密度下,碟状体的摄食率比水螅体高。经过藻类饵料适应处理的水螅体对藻类的摄食率会有显著增加,约为未经饵料适应处理的10倍。水母体对中肋骨条藻和东海原甲藻未发生摄食。     

基于神经网络模型的湛江湾水体有色溶解有机物的遥感估算

有色溶解有机物(Colored Dissolved Organic Matter, CDOM)是水体中重要的水质参数之一,是水色遥感的重要研究对象,如何构建适合特定区域的近海二类水体CDOM反演模型一直是国内外研究难点。本文利用2017年5月26～29日对南海西北部海域湛江湾20个站位采集的水样和测量的光谱资料,分析归一化遥感反射率与CDOM浓度a_g(400)的相关性,发现最大负相关系数出现在586nm处,选择580、585、590、595nm这四个波段处的归一化遥感反射率与a_g(400)建立了多元线性回归模型、BP(Back-Propagation)神经网络模型和RBF(Radial-Basis Function)神经网络模型,并与其他算法模型进行对比分析。结果发现, BP和RBF神经网络模型的平均相对误差和均方根误差均远小于多元线性回归模型和其他算法模型,神经网络模型的预测值与实测值拟合效果要优于多元线性回归模型。研究表明,神经网络模型更适合于湛江湾有色溶解有机物的遥感估算。     

热带东印度洋SST对气候变暖和变冷的响应

The response of the eastern tropical Indian Ocean(ETIO) to heat fluxes of equal amplitude but opposite sign is investigated using the Community Earth System Model(CESM). A significant positive asymmetry in sea surface temperature(SST) is found over the ETIO—the warming responses to the positive forcing exceeds the cooling to the negative forcing. A mixed layer heat budget analysis is carried out to identify the mechanisms responsible for the SST asymmetry. Results show that it is mainly ascribed to the ocean dynamical processes, including vertical advections and diffusion. The net surface heat flux, on the contrary, works to reduce the asymmetry through its shortwave radiation and latent heat flux components. The former is due to the nonlinear relationship between SST and cloud, while the latter is resulted mainly from Newtonian damping and air-sea stability effects. Changes in the SST skewness are also evaluated, with more enhanced negative SST skewness over the ETIO found for the cooling than heating scenarios due to the asymmetric thermocline-SST feedback.     

福建东山岛地质灾害特征与成因初探

海岛是海上陆地国土和人类开发海洋的远涉基地及前进支点。海岛大幅度地快速增长的开发活动与工程建设使脆弱的海岛生态环境正遭受到严重威胁。东山岛是福建第二大岛,近10年随着水产养殖与育苗、风电建设、环岛公路和房地产开发等海岛利用和开发强度的加大,海岛地质灾害及潜在风险陡增。基于现场调查和遥感影像解译,分析东山岛赋存的地质灾害类型及其分布,初步探究了主要地质灾害的诱因,为更有效地保护和可持续性开发东山岛,制定合理长效规划、防灾与减灾对策提供准确依据,并为福建及周边基岩岛的地质灾害调查与防治提供实测数据参考。