浙江沿岸上升流区叶绿素a和初级生产力的分布特征

本文叙述了1981年8月和10月在浙江近海上升流区(27°30'—30°30'N,124°00'E以西)所进行的叶绿素a含量,浮游植物优势种类、海面辐照度、海水光学参量、浮游植物光合作用速率和同化指数的测定,绘出了该水域夏季上升流盛期叶绿素a和初级生产力的分布图,并结合同步调查的海洋水文要素及化学营养盐资料,详细论述了叶绿素a和初级生产力的分布特征及其与海洋环境理化因子的关系。调查海区叶绿素a分布的高值区位于近岸和上升流锋层顶部,最大值为7.40mg/m3,真光带平均潜在初级生产力的分布,仍为近岸和上升流的中心区为高值区,调查海区上升流盛期平均现场初级生产力为1.25mgC/(m2·d),上升流中心区要超过2.0g C/(m2·d),整个水域有机碳生产量约为4.4×104t/d。     

黄海海区的叶绿素α和初级生产力

本文是对70年代末以来我国在黄海西部海区进行的叶绿素a及初级生产力调查和研究的综述。内容包括叶绿素a水平分布,垂直分布。粒径大小分级,初级生产力的季节变化,山东近岸初级生产力,浮游植物量子产值及光利用效率,初级生产力模式及利用遥感法估算叶绿素a等。结果显示,黄海初级生产力有明显季节变化,春季最高,冬季最低;高生产力区位于长江口外海及黄海北部;大部份海区年平均值在200～500mg·m~(-2)。d~(-1)(以碳计)之间,平均值在425mg·m~(-2)·d~(-1)左右。     

山东近岸黄海海域初级生产力的时空分布变化研究

于2006年8月(夏季)、2006年12月(冬季)、2007年4月(春季)、2007年10月(秋季)对山东黄海近岸初级生产力的分布进行了4个航次的调查,并对其时空分布特征进行了分析.结果显示:(1) 调查海域春、夏、秋、冬4个航次的初级生产力平均值分别为808.798,372.23,324.717和246.146 mg·m-2·d-1,春季的初级生产力最高,冬季的最低.(2) 春、夏、秋季初级生产力的变化在水平方向上总体呈现出近岸高于远岸的分布特征,而冬季的变化趋势正好相反;在垂直分布上,4个航次初级生产力均以相对海平面光强30%～10%的水层为最高,其中夏季初级生产力分层现象明显,春、秋、冬季各水层间的差异不显著.(3) 环境因子的变化对初级生产力的作用不同,利用同化指数法求得的初级生产力比14C同位素示踪法测得的数值高出1～70倍.     

胶州湾初级生产力周年变化

根据2003年5月—2004年4月逐月对胶州湾初级生产力的调查研究,分析讨论了胶州湾初级生产力的周年动态变化特征。结果表明,胶州湾初级生产力存在着明显的季节变化:夏季是一年中的高峰,平均为835.72mgC/(m2.d),春、秋季次之,分别为286.00mgC/(m2.d)和247.81mgC/(m2.d),冬季最低,平均为102.27mgC/(m2.d)。初级生产力平面分布特征为:夏季高值区一般位于湾西北部和东北部近岸水域,秋季至次年春末的高值区一般位于湾东北部近岸水域,湾中部和湾口海域较低。湾外海域除夏末秋初与湾中部水平接近外,其它季节比湾中部和湾口低,呈自湾内向湾外递降的分布趋势。6月下旬记录到7213.48mgC/(m2.d)初级生产力的最高值,位于湾东侧近岸,该高值持续时间很短,在时间上恰巧对应于一周前的一次强降雨过程。温度是影响胶州湾初级生产力季节变化的决定因子。     

基于VGPM模型的广西北部湾近岸海洋初级生产力估算

以北部湾近岸海域为研究对象,基于海洋水质监测数据与海洋初级生产力实测数据,对VGPM模型各参数分别进行校正,评估校正后的模型估算精度。结果表明:通过参数校正能够有效减小初级生产力计算误差。根据校正模型计算可得,2018年北部湾近岸海洋初级生产力变化范围为101.27～2 161.75 mg C/(m~2·d),北部湾近岸海域浮游植物在夏季和秋季对营养盐需求较为明显,在春季和冬季则无明显需求。     

福建沿岸叶绿素a及初级生产力的分布特征

本文报道了1984年5月至1985年2月福建沿岸叶绿素a和初级生产力的分布变化特征.全海区叶绿素a年平均含量为1.56mg/m3,初级生产力(C)年平均为284mg/(m2·d).各段海区叶绿素a的高峰季节有明显差异.北段海区高峰在夏季,中段在秋季,南段海区春、夏、秋变化不大.本文还就叶绿素a和初级生产力高值区的成因进行讨论.     

秦山核电站邻近水域叶绿素α和初级生产力的分布特征

本文根据1989年4月至1990年1月秦山核电站邻近水域生态基线调查资料,对叶绿素α和初级生产力作了研究。结果表明,该水域潮流急,潮差大,营养盐丰富,悬浮泥沙含量高,且叶绿素α含量比较低。 光合作用同化数随季节而异,平均值为3.07mgC·mgchla~(-1)·h~(-1)。水域现场初级生产力主要受光和水体强烈混合的限制,平均值仅为27·00mgC·m~(-2)·d~(-1)。而季节变化明显,夏季初级生产力为60.14mgC·m~(-2)·d~(-1),高于秋、春两季,冬季最低,仅为2.31mgC·m~(-2)·d~(-1)。     

南极普里兹湾浮游植物现存量与初级生产力粒级结构和新生产力研究

报道1998～1999年夏季在南极普里兹湾及其毗邻海域对细胞丰度、优势种类组成、生物量和初级生产力的粒级结构、新生产力及其环境制约机制的研究.结果表明,调查海区具有显著的空间区域化特征.普里兹湾及其毗邻陆架区浮游植物现存生物量和生产力均较高,大陆坡和深海区明显降低;营养盐浓度由于浮游植物的消耗则有相反的分布趋势.浮游植物生物量和生产力受水体的垂直稳定度、浮游动物摄食、水温和光照等环境条件的控制.粒度分级测定结果表明,对调查海区叶绿素a的贡献,小型浮游生物为52.2%,微型为29.4%,微微型为18.4%;对初级生产力的贡献,小型为52.4%,微型为28.7%,微微型为18.9%.研究海区的平均新生产力和f比分别为230.6mg/(m2·d)和0.43.     

珠江口初级生产力和新生产力研究

1996年12月和1997年8月在珠江河口湾及其毗邻海域对浮游植物生物量、初级生产力和新生产力及其环境制约机制的研究.结果表明,调查海区的叶绿素a、初级生产力和新生产力均是夏季高于冬季,冬、夏两季的平均值分别为(0.95±0.41)和(1.08±0.52)μg/dm3,(69.2±75.5)和(198.7±119.1)mg/(m2·d),(1.46±0.79)和(3.05±3.09)mg/(m3·h).冬、夏两季平均f-比分别为0.45和0.38.分级叶绿素a结果显示,冬、夏两季均以微型和微微型级分(<20μm)占优势,其对海区叶绿素a的贡献分别为796%和81.6%,对初级生产力的贡献分别为70.7%和896%.调查海区具显著的空间区域化特征,叶绿素a和潜在初级生产力的高值出现在冲淡水区的中部,向口门区和远岸区逐渐降低.现场初级生产力的高值出现在远岸区,它与复合参数B_eZ_pI₀(B_e为真光层平均叶绿素a,Z_p为真光层深度,I₀为海面光辐射强度-PAR)呈很好的正相关,说明光是研究海区初级生产力的主要限制因子.新生产力冬、夏两季的高值分别出现在交椅湾和伶仃洋西南部.     

东北季风期海南岛三亚湾初级生产力分布特征及其影响因素

根据2006年10月和2007年1月的监测资料,对三亚湾在东北季风初始期和盛行期初级生产力的分布特征及其受水体环境的影响因素进行了分析。三亚湾秋、冬季表层潜在初级生产力平均值分别为6.81mgC·m-3·h-1和7.47mgC·m-3·h-1;水柱初级生产力平均值分别为504.96mgC·m-2·d-1和495.33mgC·m-2·d-1。东北季风期间,三亚湾水体垂直混合作用加强,层化现象减弱,水动力过程和营养盐等环境因子是该海湾初级生产力分布特征和季节变化的重要调控因素;其中冬季较高的DIN分布对表层初级生产力有潜在促进作用,而水体扰动增强、真光层深度下降则导致水柱初级生产力低于秋季。三亚河口近岸水域秋、冬季均为营养盐、叶绿素a及初级生产力的高值区,其中表层潜在初级生产力在秋季和冬季分别达到了45.80mgC·m-3·h-1和39.27mgC·m-3·h-1,表明调查期间三亚河营养盐输入对近岸水体浮游植物初级生产过程的显著影响。     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

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。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

《Acta Oceanologica Sinica》Vol. 33(2014) contents

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