南沙群岛珊瑚礁潟湖及附近海区春季初级生产力

1999年 4—5月运用荧光法和14C同位素示踪法测定了渚碧礁、永暑礁、赤瓜礁、华阳礁、南薰礁5个■湖和附近海区15个站位的叶绿素a含量和初级生产力，结果表明，■湖内的平均初级生产力和平均同化系数分别为 1．52±0．90 mg C·m－3·h－1 和 6．34±1．56 mgC·（mg Chl．a）-1·h－1 。附近海区的平均初级生产力为 0．27±0．12 mg C·m-3·h-1，最大值分布在 50m水层；平均同化系数为 2．99±0．85 mg C·（mg Chl．a）-1·h-1 ，最大值分布在50m水层，最小值分布在75m水层。珊瑚礁■湖初级生产力和同化系数都比附近海区高，可能与■湖的特殊生态环境和生物群落组成有关。     

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)。     

浙江潮下带海域秋季初级生产力和叶绿素α的分市

本文报道了1982年10月浙江潮下带(北纬27°10′—30°30′,东经122°30′以西)海域叶绿素α和初级生产力的分布。表层平均叶绿素α为1.85mg·m~(-3),10米层平均叶绿素α为1.91mg·m~(-3),略大于表层。文章比较了象山港、乐清湾、东山湾和渤海湾的叶绿素α分布状况。调查海区平均初级生产力为181.17mgC·m~(-2)·d~(-1)。其值低于浙江沿岸上升流海域。     

黄海中部营养盐的贯跃层输运

黄海中部层化季节上下混合层的温差远高于其他近岸海区,温跃层较强,但通过湍流卷挟仍存在贯跃层物质输运。根据从能量平衡出发的混合层理论模型,计算了黄海中部上、下层的卷挟速度,根据3个航次调查资料,定量估计了层化季节贯跃层的营养盐输运。结果表明:下层黄海冷水团是真光层的营养盐储库,通过湍流卷挟夏季可带来15.9mgC·m-2·d-1的新生产,半个月之内它可以更新上层海洋的营养盐,与大气氮输入作用同量级,远大于大气磷输入;春秋两季贯跃层输入比大气氮输入更为重要,春秋季前者带来的新生产分别为初级生产力的21%和30%,而大气氮输入带来的新生产春季为初级生产的5.7%,秋季为初级生产的9.5%。在整个层化季节营养盐的贯跃层输运带来的新生产在整个初级生产中可能占有很大份额。秋末强风过程带来的强湍流卷挟,可在一周之内更新上层海洋的营养盐,并在风停后刺激上层初级生产的增加。     

2002年夏季南极普里兹湾及其邻近海域浮游植物现存量、初级生产力粒级结构和新生产力研究

2002年1～2月,在南极普里兹湾及其北部海区对浮游植物生物量、优势种类组成、细胞丰度、初级生产力和新生产力的观测结果表明,叶绿素a浓度、初级生产力和新生产力的高值均出现在湾内及湾口陆架区,并且远高于陆坡和深海区.湾内和湾口陆架区表层叶绿素a浓度均高于1 mg/m3,平均为(2.34±0.85)mg/m3,而陆坡区和深海区平均只有(0.19±0.14)和(0.15±0.05)mg/m3.湾内和陆架区平均初级生产力[(355.8±192.1)mg/(m2·d)]高于陆坡区[(82.0±20.8)mg/(m2·d)]和深海区[(100.5±83.4)mg/(m2·d)].在陆坡和深海区初级生产力的粒级结构以微微型浮游生物(<2 μm)对初级生产力的贡献最大(分别为49.6%和46.2%),湾内和陆架区则以小型浮游生物(为20～280 μm)的贡献为主(66.2%).在湾内和湾口陆架区同时具有较高的新生产力和再生生产力.     

桑沟湾和胶州湾沉积物耗氧率研究

为评价浅海海域底层在碳元素生物地化循环中的作用,采用现场取样培养法测定了黄海桑沟湾和胶州湾的沉积物耗氧率。桑沟湾5月和8月的沉积物耗氧率分别为15和24 mmol.m-2.d-1;胶州湾8月的沉积物耗氧率为18 mmol.m-2.d-1。回归分析表明,2个湾的沉积物耗氧率分别与沉积物表层的有机碳和总氮含量正相关。取呼吸商为0.8,得到桑沟湾底层对有机碳的矿化率占水层初级生产力的102%(5月)和67%(8月),胶州湾底层对有机碳的矿化率占水层初级生产力的28%(8月)。取桑沟湾颗粒有机碳的生物沉积速率为236 mg.m-2.d-1,得到底层对有机碳的埋置效率为40%(5月)和3%(8月),埋置的有机碳占水层初级生产力的69%(5月)和2%(8月);胶州湾颗粒有机碳的自然沉积速率为251 mg.m-2.d-1,底层对有机碳的埋置效率为32%(8月),埋置的有机碳占水层初级生产力的13%(8月)。     

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.     

黄海氮磷营养盐的循环和收支研究

建立了一个生物-物理耦合的三维营养盐动力学模型,模拟了黄海无机氮、活性磷酸盐和叶绿素a的年循环规律,估算了黄海营养盐的收支情况和季节差异,并将数值结果与实测资料进行比较。结果表明:黄海无机氮和无机磷经历了春、夏的消耗及秋、冬的补充,维持了黄海全年较高的生产力,年平均初级生产力达508mgC·m-2·d-1。黄海水文环境在很大程度上影响着营养盐的分布和生态功能:黄海中部深水区季节性热层化在春季萌发、秋末消衰,使夏季表层水营养盐匮乏,底层冷水团营养盐大量蓄集,因此初级生产力在5-6月和11月出现双峰特征,而近岸海水几乎全年混合均匀,初级生产力单峰出现在6-8月。河流每年为黄海输送225.4×103t无机氮和6.82×103t无机磷,使北黄海及近岸营养盐丰富,尤其朝鲜沿岸径流注入大量的营养盐,使其新生生产力较高,f比平均达55%。光合作用和呼吸作用是营养盐最大的汇和源,黄海中部沉积物-水界面交换向水体提供大量的硝酸氮,为新生产贡献56%的氮。大气沉降补充的营养盐占年初级生产所需氮、磷的6%和1.5%,为河流输入营养盐的3～5倍。     

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)。     

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.     

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.     

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.     

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.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

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.