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.     

莱州湾及潍河口夏季浮游植物生物量和初级生产力的分布

于1998年6月黄河断流期在潍河口及其邻近海域进行了水文、化学和生物等专业综合外业调查.对此海区浮游植物叶绿素a浓度、脱镁色素浓度和初级生产力的变化进行了分析.研究结果表明,叶绿素a浓度介于0.089～5.444mg/m3之间,平均值为1.331mg/m3;脱镁色素浓度介于0.176～3.402mg/m3之间,平均值为0.905mg/m3.叶绿素a和脱镁色素浓度高密度区分布在小清河口附近、潍河口内及潍河口以外临近海域.初级生产力介于13.58～301.54mg/(d·m2)之间,平均值为62.49mg/(d·m2).水柱初级生产力高值区分布在小清河口和37.30°N,119.47°E附近.对水文、化学和浮游动物等环境因子与浮游植物生物量和初级生产力的相关性分析表明,整个调查区,浮游植物生物量和初级生产力与海区潮汐、光照、磷酸盐、硅酸盐和微型浮游动物等环境因子密切相关,同氨盐、硝酸盐和亚硝酸盐的作用不明显,其中潍河口内浮游植物的生物量分布同潮汐的关系最为密切.夏季此海域浮游植物生长主要受磷酸盐和硅酸盐的限制.调查海域浮游植物生物量及生产力水平较历史同期有所增加.     

热带太平洋西部及赤道暖水区的初级生产力

描述了对热带太平洋西部(1991年11月WOCE调查)及赤道暖水区(1992年11月至1993年2月的TOGA-COARE调查)的叶绿素a分布和初级生产力(C),及其与理化环境的关系.西部海域叶绿素a平均总量达19.79mg/m2,暖水区为2.168mg/m2;暖水区的潜在初级生产量高于西部海域,量值分别为228mg/(m2·d)和171mg/(m2·d),次表层最大值成为调查海域水体叶绿素a分布的一个明显特点.叶绿素a总量平面分布趋向表明:高生物量主要位于巴士海峡邻近、菲律宾以及伊里安岛的近岸站位,此外,在2°～4°N之间的观测区.低生物量主要位于外洋海域.生物量的分布与不同海域的物理过程变化有关,而海水涌升可能是导致温度、盐度和营养盐分布产生变化,并因而导致高生物量的一个重要的物理过程.     

南海北部初级生产力遥感反演及其环境调控机制

选取VGPM模式对南海北部海域初级生产力进行反演,通过SeaWiFS和AVHRR提供的Chl a,K₄₉₀,PAR和SST等遥感数据产品计算得到了模式所需的各项参数,结合现场实测数据对模式进行了修订和误差分析.在此基础上通过反演计算获得了南海北部海域7 a平均(1998～2004年)初级生产力逐月分布图像.研究结果表明,研究海域初级生产力(C)分布趋势为由沿岸带向陆架以及外海逐渐降低,其中沿岸带区高于400 mg/(m2·d),外海区大致在100～300 mg/(m2·d);初级生产力水平冬季最高[平均为608 mg/(m2·d)]、夏季最低[平均为292 mg/(m2·d)],春、秋季基本持平.控制初级生产力时空分布的因子主要有营养盐、温度、光照,其中又以季风和环流驱动下的营养盐变化对初级生产力的调控最为显著.     

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.     

广东流沙湾叶绿素a含量和初级生产力状况的研究

对流沙湾叶绿素a含量和初级生产力周年调查结果表明, 流沙湾叶绿素a含量变化在0.09—25.35mg/m3之间, 平均2.91mg/m3。叶绿素a含量有明显的月变化, 各站位叶绿素a含量在3—5月份较低, 最高出现在8月份和11月份, 平均4.58mg/m3, 出现二个峰值。同一站位不同月份叶绿素a含量总体上差异显著(P<0.05)。流沙湾的初级生产力变化范围是6.89—1482.55mgC/(m2·d), 平均242.74mgC/(m2·d)。初级生产力不同月份存在着明显的差异, 其中, 11月份最高, 8月份和翌年1月份次之, 3—5月份初级生产力处于最低水平。流沙湾叶绿素a含量和初级生产力有明显的水平分布, 最高值出现在湾中央处的4号站和湾北部的5号站, 最低值出现在湾口西部的1号站和湾底南部的9号站, 各站位之间总体上差异显著(P<0.05)。     

西北太平洋海洋净初级生产力与柔鱼资源量变动关系的研究

海洋初级生产力在海洋生态中扮演重要角色,其变化影响了海洋渔业的潜在产量。本文根据2004-2013年中国鱿钓组提供的西北太平洋柔鱼(Ommastrephes bartramii)捕捞数据和海洋遥感净初级生产力数据,研究了柔鱼冬春生西部群体资源量变动与净初级生产力的关系。结果发现,柔鱼渔场范围内净初级生产力在经度方向上呈明显的季节性变化,冬春季低,夏秋季高。捕捞月份7-11月对应的适宜净初级生产力范围分别为500~700 mg/(m2·d)(以碳计),500~800 mg/(m2·d),500~1000 mg/(m2·d),500~800 mg/(m2·d)和300~500 mg/(m2·d),最适净初级生产力分别为700 mg/(m2·d),600 mg/(m2·d),700 mg/(m2·d),600 mg/(m2·d)和400 mg/(m2·d)。7-11各月最适净初级生产力平均纬度与捕捞努力量纬度重心呈显著正相关关系(P<0.05),说明了捕捞努力量位置在渔场中不是随机分布,可能受最适净初级生产力的纬度分布的影响。柔鱼年间资源丰度与各年3月份净初级生产力以及7-11月份平均净初级生产力大小显著正相关(P<0.05)。推测每年柔鱼资源量大小可能是由3月份产卵场海域和7-11月捕捞月份渔场净初级生产力水平交互作用的结果。研究表明,异常环境条件(厄尔尼诺和拉尼娜事件)对柔鱼产卵场和渔场的净初级生产力具有显著影响,但调控机制不同。     

东北太平洋中国合同区的叶绿素a和初级生产力

根据东北太平洋中国合同区东区和西区从1994年至2003年6个航次(DY85-4,DY95-7,DY95-8,DY95-10,DY105-11和DY105-12.14)初级生产力调查资料编写.结果表明:次表层高值分布为叶绿素a分布的一般特征,从表层至水深50 m,数值为0.1 mg/m3左右,在水深50~100 m上下,数值约在0.2~0.4 mg/m3之间,在水深大于100 m,特别是150 m以深数值逐渐减小为零;东区初级生产力(C)测值在76.8~191.9 mg/(m2·d),平均为116.1 mg/(m2·d);西区的在73.1~222.5 mg/(m2·d),平均为127.1 mg/(m2·d);在水深0~125 m,0.2~2μm颗粒的微微型浮游植物的叶绿素a比例占叶绿素a总量的70%以上,而在水深125 m以深,占50%以下;反之,2~20μm和大于20μm两种粒级所占比例的和在0~125 m深度范围占30%以下,在水深125m以深时为50%以上.调查显示东、西两区属于初级生产力比较低的海域.     

2011 年春、夏季黄、东海叶绿素a和初级生产力的时空变化特征

依据2011年春、夏两季黄、东海调查资料,分析了叶绿素a和初级生产力的空间分布和季节变化特征,并分析了主要影响因素。南黄海、东海北部春季叶绿素a平均含量为74.83mg/m2,夏季为23.84mg/m2,春季明显高于夏季。春季大部分海域叶绿素a含量垂直分布均匀,夏季则出现较为明显的分层现象,在次表层出现最大值。初级生产力水平春季为993.9mgC/(m2.d),夏季为1274mgC/(m2.d),与1984—1985年相比有所升高。春季高值区出现在黄海中部及长江口附近海域;夏季高值区主要分布在山东半岛南岸近海海域、长江口外的黄、东海交界海域以及浙江省沿岸海域。春季整个调查海区叶绿素a浓度与磷酸盐浓度呈显著负相关,与氮磷比呈显著的正相关性,表明黄、东海春季磷酸盐可能成为浮游植物生长的一个限制因子。     

刘公岛水域内叶绿素-α含量和初级生产力

据1990年11月至1991年8月间调查资料，提出刘公岛水域内叶绿素－a含量的时空分布和初级生产力的分布与变化。指出此分布与该水域温度和营养盐含量密切相关。叶绿素－a含量以春季最高，冬季次之，秋季稍低，夏季最低。年变幅为0．21～2．45mg／m3，年平均值为1．02mg／m3。初级生产力以夏季最高，春季次之，秋季略低，冬季最低，年变幅为33．40～512．72mg·c／m2·d，年平均值为181．15mg·c／m2·d。     

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.     

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.     

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。     

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.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

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.