长江口湍流剖面的观测与分析

小尺度湍流过程对河口物质输运与能量交换至关重要。受传统观测方法的限制, 河口浅水区域的剖面观测资料至今较为匮乏, 进而限制了湍流过程的研究。为此, 采用新型5波束声学多普勒流速剖面仪(Nortek Signature 1 000 kHz AD2CP)在长江口开展湍流剖面观测, 获取高频、低噪的高质量湍流剖面数据, 并与声学多普勒点式流速仪(acoustic doppler velocimeters, ADV)同步观测的数据进行对比。结果表明, 通过AD2CP与ADV获得的近底部边界层摩阻流速u_*、拖曳系数C_d、雷诺应力S_R等特征参数基本一致, 底摩擦与波浪能量为河口区域湍动能的主要输入源。湍流垂向结构存在显著的非局地平衡, 即温盐等斜压作用引起的浮力通量、对流项以及强波浪作用影响的脉动压力做功、黏性输运等因素可能为长江口湍流非局地平衡的主因。     

珠江河口底边界层湍流特征量研究

通过高频流速仪ADV和脉冲相干声学多普勒剖面仪PC-ADP对珠江河口崖门底边界层进行了三个测次潮内(25 h)顶点连续观测,利用观测数据计算分析了潮流底边界层内的湍流特征量及其时空变化.结果表明:1)对于半日潮流占优的河口,各湍流特征量均具有明显的四分之一周日的变化规律;2)湍流强度、床底应力和摩阻流速在潮内的平均值以位于河口湾的测点所测值最大,依次向上游递减,而湍动能耗散率则沿河口湾至上游逐渐增大;3)三个测次边界层内涡动粘滞系数的平均值分别为2.42×10 -3 m 2/s、2.20×10 -4m 2/s和6.16×10 -4 m 2/s,拖曳系数的均值为7.89×10 -3、1.63×10 -3和1.99×10 -2,两者潮内的变化均非常显著,相差可达一到两个数量级;4)在充分混合的潮流底边界层内,湍动能生成与耗散基本处于局部平衡状态,三个测次湍动能耗散率均值在8.89×10 -5 W/kg～7.43×10 -6 W/kg之间.     

底边界层水沙观测系统和应用

利用现代先进的光学和声学测量仪器(ADP、PC-ADP、ADV、OBS等),组制四角架观测系统用于底边界层的水沙观测.此观测系统既可获取垂向流速场,更可获取常规水文观测难以获取的高分辨率的近底流速、近底单点紊动过程、近底温盐沙和波浪过程.利用此观测系统于2007年8月在长江口北槽最大浑浊带内进行了实地观测.分析四角架观测数据与同步船测底部数据表明,四角架观测系统在近底(特别是底部明显分层)观测时表现出明显优势.常规水文观测测得底部含沙量一般只相当于距底70～120 cm高度含沙量;船测底部最大含沙量为5.8 kg/m 3,而架测距底30 cm处最大含沙量有25 kg/m 3;近底含沙量较高时往往出现强分层,强分层时实测距底30 cm处含沙量可达距底120 cm处含沙量的5倍;船测底部流速比架测距底30 cm处流速平均偏大45%;但距底30 cm处最大流速仍可达1.2 m/s.船测数据也验证了四角架观测数据的正确性.     

长江河口区边界层参数的观测与分析

2003年11月在长江口南槽用ADCP进行定点水文观测,结果表明研究区为不规则半日潮,在水流转向期流速较低时常出现悬沙浓度峰值。根据流速对数剖面分布模型与悬沙分布模型,分别计算了海底边界层参数,其中潮周期内摩阻流速可达0.15 m/s,粗糙长度为0.01~1.2 m,拖曳系数为10-3~10-4,边界层厚度为2~4 m,悬沙的沉降速率为0.2~6 mm/s。     

长江口浑浊带核心区北槽水动力特征研究

本文根据2015年长江口洪季浑浊带水域座底三脚架全水深范围观测数据,对北槽中下段纵横向流、余流结构、边界层特征等进行了深入研究,结果显示:（1）大潮潮流矢量特征在垂向上的变化差异最为显著;北槽中下段水流出现明显的横向输移,指向航槽北面;（2）横向流速在大潮期间的变化（垂线平均）为-0.10~0.39 m/s,小潮期间的变化为-0.13~0.25 m/s;横向平流对于北槽纵向物质输运有显著调整作用;（3）余流垂向差异大,底部几乎为0,小潮期间余流更强;周期性再悬浮的细颗粒泥沙可作为北槽最大浑浊带的重要物质来源;（4）传统六点对数流速拟合法获得摩阻流速误差较大,近底1 m区域高分辨流速剖面是准确获取底边界层参数的有效途径。     

粗糙地形内潮导致混合的实验研究

内潮是海洋能量级串中重要环节,对维持海洋背景层结及大尺度环流结构起着重要的作用。本文设计了粗糙地形内潮导致混合的实验方案,对内潮混合机制进行了探讨。根据混合机理将流场分为三个区域:底边界层区、近底边界层区及远离边界层区。利用PIV及ADV观测内潮流场中断面的流速,计算并对比了两者的无量纲流速振幅、雷诺剪切应力及湍耗散率。对比结果良好,实验方案可用于内潮混合的实验研究。     

围填海对芝罘湾潮流场和纳潮量的影响研究

本文基于MIKE21水动力数值模型,以1985年、1993年、2010年和2017年4个时期为代表年份,定量识别了芝罘湾围填海工程引起的潮流场及纳潮量的变化情况。结果表明:(1)流场:潮流以往复流运动为主,湾口流速最大可达32.99 cm/s,湾底流速较小,最大为9.49 cm/s,湾口流速远大于湾底流速。围填海工程使湾内流速发生了明显变化,湾内9个代表点位的流速均有所减小,湾口流速变化率较小,湾顶流速变化率较大,2017年湾底流速相比于1985年最高减小量达到39%。(2)纳潮量:芝罘湾在围填海前后4个时期的纳潮量分别为4.701×10~(7 )m~3、4.469×10~(7 )m~3、3.854×10~(7 )m~3和3.690×10~(7 )m~3,对比发现,围填海工程的进行使湾内面积持续减小,纳潮量也持续减小,1985-2017年减小了21.51%,围填海工程弱化了芝罘湾的水动力条件。     

ASM-IV仪器在河口近底层悬沙浓度观测分析中的应用研究

近底层悬沙时空变化对于理解河口冲淤变化有着至关重要的作用。然而,长期以来河口近底层水体悬沙浓度的连续变化大都是基于单点观测数据或水样处理获取。基于此,本研究利用光学仪器边界层悬浮物剖面测量仪(Argus Surface Meter IV,ASM-IV)获得长江口南槽近底层进行连续10 d的实测数据,探讨ASM-IV仪器监测悬沙浓度精度的有效性。结果表明:(1)传统仪器布设方法所获取的数据,相对误差高于基于ASM-IV所测误差,在大、中及小潮期间的平均误差值分别为24.15%、17.31%和16.18%;越靠近底部河床,相对误差从距底52 cm向下随距底距离的减小而逐渐增大;(2)对于近底层单宽悬沙通量测量结果而言,传统测量仪器布设方法所测量数值一般偏小;(3)大潮时期近底层1 m内的水体悬沙分布均匀,分层不明显;在中、小潮时期,与近底层1 m内平均悬沙浓度相差最大的点皆位于距底20~50 cm附近。因而,近底层悬沙浓度测量时间在大潮时期或越靠近底层,利用ASM-IV监测近底层悬沙浓度值更为准确。中、小潮时期利用单点或采集水样测量时,选取0.8H层水体悬沙浓度代替近底层悬沙浓度较最底部水体悬沙浓度更为准确。     

ASM-Ⅳ仪器在河口近底层悬沙浓度观测分析中的应用研究

近底层悬沙时空变化对于理解河口冲淤变化有着至关重要的作用。然而,长期以来河口近底层水体悬沙浓度的连续变化大都是基于单点观测数据或水样处理获取。基于此,本研究利用光学仪器边界层悬浮物剖面测量仪(Argus Surface Meter Ⅳ,ASM-Ⅳ)获得长江口南槽近底层进行连续10 d的实测数据,探讨ASM-Ⅳ仪器监测悬沙浓度精度的有效性。结果表明:(1)传统仪器布设方法所获取的数据,相对误差高于基于ASM-Ⅳ所测误差,在大、中及小潮期间的平均误差值分别为24. 15%、17. 31%和16. 18%;越靠近底部河床,相对误差从距底52 cm向下随距底距离的减小而逐渐增大;(2)对于近底层单宽悬沙通量测量结果而言,传统测量仪器布设方法所测量数值一般偏小;(3)大潮时期近底层1 m内的水体悬沙分布均匀,分层不明显;在中、小潮时期,与近底层1 m内平均悬沙浓度相差最大的点皆位于距底20～50 cm附近。因而,近底层悬沙浓度测量时间在大潮时期或越靠近底层,利用ASM-Ⅳ监测近底层悬沙浓度值更为准确。中、小潮时期利用单点或采集水样测量时,选取0. 8H层水体悬沙浓度代替近底层悬沙浓度较最底部水体悬沙浓度更为准确。     

桐花树红树林潮滩近底层悬沙浓度垂向剖面变化特征分析*

观测红树林潮滩在波浪和潮流作用下的近底层垂向剖面悬沙浓度变化过程, 对理解海岸带植被的消能促淤机制和滨海湿地生态修复工程有着重要作用。本文以北部湾七星岛岛尾桐花树红树林潮滩为例, 基于剖面流速仪HR、声学多普勒单点流速仪ADV、浪潮仪T-wave及剖面浊度仪ASM, 获取了研究区域2019年夏季大潮连续3天的水文数据, 同时结合桐花树典型植株实测参数, 分析了潮周期内红树林潮滩近底层垂向剖面悬沙响应波浪、潮流作用及桐花树空间结构的运动过程。结果表明: 1) 桐花树潮滩近底层悬沙浓度和悬沙通量具有涨潮明显大于落潮的潮汐不对称现象, 剖面垂向高悬沙浓度区域在涨潮初期—涨急由距底部0.1~0.37m转变为距底部0.5~0.67m, 落急—落潮末期则由上部转变为下部; 2) 潮周期内悬沙起动和再悬浮阶段发生在以波浪作用主导的涨潮初期和落潮末期, 平流和沉降发生在以潮流作用为主的涨急至落急整个阶段; 3) 涨潮阶段桐花树冠层的茂密枝叶通过减缓流速拦截多于冠层上部40%以上的悬沙, 落潮水体则挟沙自陆向海经过桐花树群落, 使得悬沙浓度下降超过71%。该不对称涨、落潮动力沉积机制有利于悬沙向岸输运, 促进潮滩扩张过程。     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Estimation of Sediment Properties during Benthic Impact Experiments

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans. The estimates show that the weights of dry (355-1332 t) and wet sediment (1651-4888 t) recovered during the experiments, are not only a function of the total duration and distance covered during the experiment, but also depend on water content and density of the sediment. Estimation of dry sediment and its volumetric ratio in the discharge, are key parameters for calculating the discharged volume. The estimated volume of wet sediment recovered (1427-4049 m 3 ) as well as discharged (2693-6951 m 3 ) during the experiments, provide important inputs to evaluate the sediment resettlement and migration. Using these estimates, the average depth of excavation on the seafloor, can also been calculated. However, the stages of sediment recovery and discharge are expressed differently in some of the experiments. In order to standardize these, different stages have been identified, and definitions of certain terms have been suggested, for use in the future. The methods of calculating different properties, as well as weight and volume of discharged sediment are described in the paper for use in other applications concerning deep-sea discharges.     

A Tidal Flow Model for the Gulf of Kachchh, India

A vertically integrated model has been used to study the tidal circulation and currents in the Gulf of Kachchh along the west coast of India. The model is fully nonlinear and uses a semiexplicit finite difference scheme to solve the basic hydrodynamic equations on a staggered grid. The model is forced by prescribing the tides along the open boundary of the model domain. The flow is simulated both with and without the presence of the proposed tidal barrage across the Hansthal Creek in the Gulf of Kachchh. The results show a considerable change in the behavior of the tidal flow in the presence of the barrage.     

利用中国GF-3卫星SAR和HY-2A卫星微波散射计的首次台风联合定量观测

<正>The typhoon,as a mature tropical cyclone that develops in the western part of the North Pacific Ocean with high wind speed and heavy rainfall,is one of the most lethal and costly of natural disasters for the densely populated countries of East Asia.It can be easily detected by space-borne sensors operated at microwave,visible or infrared bands(Liu et al.,2014).Synthetic Aperture Radar(SAR)is     

离子交换—原子吸收光谱法测定海水中痕量铜、铅、锌、镉、铁、锰

本文介绍了用国产D401型螯合树脂分离富集海水中铜、铅、锌、镉、铁、锰等痕量元素,并用原子吸收光谱仪测定其含量的方法。讨论了各元素的分离条件选择及干扰元素的影响,并与溶剂萃取法的结果作了比较。各元素检测的定量下限为:铜0.5μg/L、铅0.1μg/L、锌1.0μg/L、镉0.01μg/L、铁2.0μg/L、锰2.0μg/L。方法精密度在4—8％之间,回收率为90—102％。     

Biogeochemistry of Mangrove Soil Organic Matter: a Comparison BetweenRhizophoraandAvicenniaSoils in South-eastern Brazil

Soil core samples fromRhizophora mangleL. andAvicennia schauerianaStapf & Leech forests from south-eastern Brazil were analysed for their total organic matter content and their sugars, amino acid and amino sugars composition. Organic carbon and nitrogen contents were higher inAvicenniathan inRhizophorasoils. The contribution of sugars and amino acids to the total organic carbon pool was constant with depth inRhizophorasoils whereas inAvicenniasoils it increased. Spectral distribution of sugars and amino acids showed a dominance of Ca-affine monomers, particularly acidic amino acids, and the sugar arabinose. Biogeochemical indicators derived from ratios of individual sugar and amino acid monomers confirm previous studies which showed that organic matter in both soils is mainly of mangrove origin. The results further suggest accumulation of organic matter inRhizophorasoils and a continuing degradation of organic matter inAvicenniasoils. The latter may thus release more nutrients to adjacent ecosystems thanRhizophorasoils.     

A review of orange roughy Hoplostethus atlanticus fisheries,estimation methods,biology and stock structure

Orange roughy Hoplostethus atlanticus are unusual fish. They form dense aggregations that have fuelled lucrative fisheries at great depths (600–1 400 m), especially off Namibia, New Zealand and Australia. They are thought to be very long-lived (>100 years, maturity at 22 – 40 years), and to have exceptionally low natural mortality (M = 0.045–0.064 year^?1) and slow growth rates (K = 0.055–0.070 year^?1). In addition, they spawn large eggs and have low fecundity. These factors combine to make orange roughy highly susceptible to overfishing; most stocks are below 30% of pristine levels. Assessments are obtained from indices of catch rate and trawl, acoustic and egg surveys. Acoustic estimates are the most direct, but are confounded by the species' low target strength (?50 to ?53 dB)–attributable to the wax-filled swim bladder. Extracellular wax esters are stored in abundance and comprise mostly mono-unsaturated fatty acids, with low concentrations of the ω-3 fatty acid family. This unusual composition (resultant from the species' diet) ensures neutral buoyancy. Stock separation has been inferred mainly from biological studies, but genetic studies have also found differences among stocks within New Zealand and Australia. Deep-water habitat may be damaged by trawling operations and may take many years to recover, so in some quarters there is a call for a portion of suitable habitat to be set aside for preservation. Although Namibian orange roughy are shallower, smaller and younger than those in other stocks, the Namibian fishery sustained high catches for only a few years before quotas were reduced, from 12 000 to 1 875 tons. Three management lessons are suggested for developing orange roughy fisheries based on the Namibian experience: (1) imposition of catch limits during exploratory fishing; (2) starting the acoustic surveys earlier in the fishery, if possible; (3) greater reliance on trends in catch rate until a survey series has been established.