Acquisition and Inversion of Dispersive Seismic Waves in Shallow Marine Environments

Two types of dispersive seismic waves have been acquired in different geological settings to investigate the potential to reveal the elastic parameters of the shallow marine subsurface. Scholte waves as well as acoustic guided waves are excited by a near-surface towed airgun, and recorded using two acquisition methods: (1) the towed-acquisition system using a hydrophone streamer towed close to the sea floor, and (2) the stationary-receiver method using Ocean-Bottom Seismometers and/or Hydrophones (OBS/OBH). Our diverse data sets reveal that the spatial sampling of the wavefield required to avoid aliasing may vary significantly for different geological settings. Scholte waves are characterised by a few distinct modes observed at low frequencies and low phase velocities. Their dispersion is mainly controlled by the depth profile of the shear-wave velocity. Acoustic guided waves show profound amplitude variations of numerous higher modes over a broad frequency range. These are sensitive to shear-wave velocity, but more sensitive to compressional-wave velocity than Scholte waves are. To avoid the identification of distinct modes we infer 1-D models of elastic parameters of the subsurface from the inversion of the full wavefield spectra of acoustic guided waves. In the Siberian Laptev Sea we infer the presence of a soft sediment layer (8–10 m) with a well resolved strong S-velocity gradient (150–450 m/s). In the Baltic Sea a low P-velocity layer with a strong vertical gradient (1250–1440 m/s) corresponding to a post-glacial gassy mud layer could be resolved, which agrees well with the sediment stratigraphy derived from a gravity core.     

In situ Observations on Contraction Behaviour and Diel Activity of Halcampoides purpurea var. mediterranea (Cnidaria, Anthozoa) in a Marine Cave

Abstract. The contraction behaviour of the sand-dwelling sea anemone Halcampoides purpurea var. mediterranea was observed in situ in a cave of the Penisola Sorrentina (Gulf of Naples). The circadian rhythm of activity of two specimens, together with migrations of mysidacean swarms in and out the cave, was studied with time-lapse photography.     

海洋沉积物中碳的来源、迁移和转化

人类活动每年向大气排放的CO2约为65亿t，其中留在大气中的约占50%，大洋吸收约16亿-20亿t，陆地生态系统大约吸收0.7亿~1.4亿t(Bates，2001；Battle et al.，2000),还有大约13亿t找不到去处，称为大气CO2丢失项，而陆架边缘海有可能是这丢失项的去处。近海沉积物是大气二氧化碳的接受者，同时当条件合适时沉积物中的碳又可被释放重新进入水体乃至大气中，是碳循环中的重要源与汇，因此海洋沉积物在碳循环中的作用是全球碳循环的一个关键环节。虽然近十年来这方面的研究已经引起众多学者的关注，对沉积物中的碳循环进行了较大量的研究，取得了一系列成果，但海洋沉积物在碳循环中的作用和过程至今并未查清，具体体现在海洋沉积物在海洋碳循环中起什么作用？起多大作用？在哪些方面影响和控制海洋碳循环？这些均需要科学家们长期的艰苦努力，以便在更深入、更系统和更高层次上研究解决困扰当今人类的涉及碳循环这一重大环境科学问题。 海洋沉积物为海洋环境中的一个主要研究对象，其中的碳与水体-生物体以及大气、入海河流等进行着不间断的交换、大气中的气体碳经过复杂的海洋生物地球化学过程转化为水体中的溶解碳，再变为颗粒碳，经沉降最终形成沉积物，在适宜的条件下上述的反过程同样会发生。因此，研究海洋沉积物中的碳在其循环中的作用是非常困难的。碳是最主要的生源要素，更是生命活动能流、物流中最重要的元素，几乎所有的生物地球化学循环过程都与它有关，因而有关碳循环的研究是目前全球变化研究的热点。许多国际研究计划均以此为核心研究内容。如国际地圈与生物圈计划(IGBP)中的全球海洋通量联合研究(JGOFS)、全球生态系统动力学(GLOBEC)以及上层海洋与低层大气研究计划(SOLAS)等(唐启升，2001；宋金明，2000)。碳循环研究以 JGOFS计划2001年基本结束为标志，通过近十几年的研究，取得了丰硕的成果，系统了解了海洋循环的过程及界面碳通量，对全球碳循环也有了一个初步的了解。为进一步深入开展这方面的研究作者从海洋沉积物中碳的形态与来源、海水及颗粒物中碳与沉积物碳的关系、表层沉积物再悬浮对碳循环的影响以及沉积物中碳的早期成岩作用等几个方面阐述了海洋沉积物中碳循环目前的研究进展。     

Probabilistic Durability Assessment of Concrete Structures in Marine Environments: Reliability and Sensitivity Analysis

A probabilistic framework for durability assessment of concrete structures in marine environments was proposed in terms of reliability and sensitivity analysis, which takes into account the uncertainties under the environmental, material, structural and executional conditions. A time-dependent probabilistic model of chloride ingress was established first to consider the variations in various governing parameters, such as the chloride concentration, chloride diffusion coefficient, and age factor. Then the Nataf transformation was adopted to transform the non-normal random variables from the original physical space into the independent standard Normal space. After that the durability limit state function and its gradient vector with respect to the original physical parameters were derived analytically, based on which the first-order reliability method was adopted to analyze the time-dependent reliability and parametric sensitivity of concrete structures in marine environments. The accuracy of the proposed method was verified by comparing with the second-order reliability method and the Monte Carlo simulation. Finally, the influences of environmental conditions, material properties, structural parameters and execution conditions on the time-dependent reliability of concrete structures in marine environments were also investigated. The proposed probabilistic framework can be implemented in the decision-making algorithm for the maintenance and repair of deteriorating concrete structures in marine environments.     

Population Parameters, Life Cycle, and Feeding of Mysidium columbiae (Zimmer) in the Waters Surrounding a Belizian Mangrove Cay

Abstract. The ecology of tropical Mysidacea is poorly known. Mysidium columbiae (Z immer ), because of its ubiquitous distribution in the tropical western Atlantic and the information available on its aggregative behavior, is an ideal subject of study to reconcile aspects of this problem. Information and data were obtained on abundance, population size, shoal/school structure, fecundity, development, and feeding of a M. columbiae population inhabiting waters surrounding Twin Cays, a mangrove archipelago in Belize. Although reproduction was continuous and proportions of life stages within shoals remained relatively constant throughout the year, population size decreased by an order of magnitude from summer to winter. Embryonic development averaged 4.7 days, with postlarvae being released near the surface before dawn. Aquarium experiments suggested that olfaction may be more sensitive than vision, although both senses were used to locate food. This species is a detritivore, but gut contents suggested that it may also be a predator.     

The European Atlas of the Seas: Relating Natural and Socio-Economic Elements of Coastal and Marine Environments in the European Union

The European Atlas of the Seas is a web-based information system aimed at the general public, but it is also capable of supporting selected nonspecialist professionals in addressing environmental issues, human activities, and policies related to the coast and sea. It includes a collection of maps and associated fact sheets based on data originating primarily from the European Commission and its agencies, which present a snapshot of key natural and socio-economic elements of the coastal and marine regions of the European Union. It provides a suite of basic instruments for map analysis and data combination to derive ad hoc maritime indicators.     

Some Aspects of Diet and Foraging Behavior of Octopus dofleini Wülker, 1910 in its Northernmost Range

Abstract. Diet and foraging behavior of Octopus dofleini in Prince William Sound and Port Graham, Alaska, were studied from collections of den litter, measurements of octopuses and estimates of live prey abundance. Based on 193 den collections from depths of - 31 to + 1.3 m, a diet of hard-bodied prey could be identified. The five most common litter species made up 80% of the litter remains, with nearly 30 species of various taxa malung up the rest. The proportions of major hard-bodied prey species in each litter pile significantly differed with depth of den, associated substrata, presence of cobble and geographical location but not with the presence of boulders or outcrop, the density of kelp or season of litter collection. Octopus weight was not significantly correlated with the size of prey remains although O. dofleini may take a wide range of prey sizes once it reaches 2.5 kg. O. dofleini was more likely to be found at sites with crabs, although no litter species was significantly preferred over its estimated abundance, and one species was significantly avoided. These results suggest that O. dofleini includes suitable bivalve and crab species in its diet in relation to live abundance, while at the same time exercising an element of selectivity, as some species were actively avoided. Comparison of litter remains from the northern-most range of O. dofleini with those published for British Columbia show that diet breadth was similar, but the identity of major hard-bodied prey species was very different for Alaskan octopuses.     

ENDECO水流计在实际使用中不可忽视的几个问题及解决方法

ＥＮＤＥＣＯ水流计在实际应用中往往由于操作者一时疏忽而使仪器不能正常工作,乃至造成难以弥补的损失。本文提出了在实际操作中不容忽视的几个问题并介绍了解决的方法。     

On the Occurrence of Marine Fungi in the Diet of Littorina angulifera and Observations on the Behavior of the Periwinkle*

Abstract. The feeding and resting patterns of Littorina angulifera, the southern periwinkle, were observed in mangrove habitats of Belize (Central America). The snails feed predominantly on the surface of prop roots of Rhizophora mangle in a narrow zone at and above the mean high water mark. This area contains large numbers of hyphae and chlamydospores of an unidentified marine fungus (Deuteromycetes) and filaments of a chlorophyte (Chlorochytrium sp.). Both organisms are ingested by snails whose digestive tracts and fecal pellets contain ground-up cork cells, tricho-sclereids, tracheids, calcium oxalate crystals, fungal hyphae and chlamydospores, as well as undigested cyanobacteria. Most fungal particles pass through the gut unchanged. During dry periods, L. angulifera is in a dormant state, usually attached with dried mucus to leaves high in the tree, causing necrotic, crescent-shaped marks. The leaf tissue under the area of shell attachment becomes meristematic, separating dead tissues from healthy mesophyll. The snails detach during rainfall and move downward to the feeding sites on the prop roots.     

Accumulation and Cycle of Heavy Metals in Sonneratia apetala and S. caseolaris Mangrove Community at Futian of Shenzhen, China

Wetland ecosystem in the Shenzhen Bay is one of the internationally important ecosystems in South China Region. Its core, with the Mai Po Mangrove Nature Reserve in Hong Kong on the one side and the Futian Mangrove Nature Reserve in Shenzhen on the other side, provides habitats for many rare and endangered wild birds, especially for migratory birds[1, 2]. With the economic development in Hong Kong and Shenzhen, a large mount of silt and untreated waste water are poured into the Shenzhe…     

Population Dynamics and Life History Characteristics of the Blue Crabs Callinectes similis and C. sapidus in Bay Environments of the Northern Gulf of Mexico

Abstract. The population dynamics and life history characteristics of Callinectes similis and C. sapidus in the Mobile Bay-Mississippi Sound estuarine system of the northern Gulf of Mexico were studied. We report that C. similis is numerically dominant in open-bays, while C. sapidus is more abundant in shallow salt marshes. Juvenile C. similis recruit into both open-bays and salt marshes, but juvenile C. sapidus primarily recruit into shallow salt marshes. Sex ratios of C. similis and C. sapidus were generally skewed towards higher proportions of males than females. Callinectes similis appears to have a life cycle similar to that of C. sapidus. Egg-carrying C. similis migrate to higher salinity waters and presumably release larvae to nearshore shelf waters; following development, the larvae re-invade estuaries as megalopae. Juvenile C. similis grow more slowly than C. sapidus. This may be attributable to reduced feeding rates. Marked differences in fecundity and reproductive effort were found between these species. Callinectes similis and C. sapidus , respectively, produced 2.4–5.5 times 10⁵ and 2.1–3.2 times 10⁶ eggs and invested 24–49 and 171–372 kJ per brood. Rhizocephalan barnacle infestation by Loxothylacus texanus was encountered in C. sapidus , while sympatric C. similis were free of this rhizocephalan parasite.     

海带属褐藻生物学研究成就与进展

以海带(Laminaria ja ponica Aresch)为重点，综述了海带属褐藻生物学研究成就，介绍了海带属褐藻遗传育种技术、育苗技术和分子生物学研究进展。海带属褐藻生物学研究基础好，种质资源丰富，经济、生态价值高，是进行大型海藻遗传学和基因组学研究的理想材料。     

HNO3-HClO4-原子吸收分光光度法测定海洋生物体中Cu,Pb,Zn,Cd,Cr

参考《海洋监测规范第6部分:生物体分析》(GB17378.6-1998)的规范方法,采用单一HNO3-HClO4常压方法消化贻贝成分分析分析标准物质(GBW08571)。取样量为0.500g时,在加热温度为160℃～210℃,加入10mL HNO3、2mLHClO4,加盖加热7h左右,最后的样品消化液赶酸赶净的条件下,样品消化液直接以原子吸收分光光度计测定,其中Cu,Pb,Zn,Cd,Cr的测定值都在标准值范围之内。并着重对比温度对消化效果的影响以及Cu,Cd以火焰法与无火焰法测定的差别。     

大陆型山谷冰川冰震的规律和影响因素——以老虎沟12号冰川为例

2015年10月,利用便携式宽频带地震仪在祁连山老虎沟12号冰川上进行了9 d的冰震观测,在台站的震动信号中识别出大量与冰川动态特性相关的冰震。根据信号的频率等特征,可将其分为短周期冰震和长周期冰震。短周期冰震的持续时间大多在0.1 s以下,频谱集中在20~100 Hz之间,其数量可达每天6 600个,占所检测到冰震的绝大部分。长周期冰震持续时间可达几十秒至数小时,其地震波形频率集中在0.1~10 Hz,观测期间检测到296次长周期冰震。对比冰震发震时间和当地气温发现:气温下降,短周期冰震事件数量快速增加;气温升高,短周期冰震数量逐渐减少。短周期冰震的发震时间分布呈现出以1 d为周期变化的特征。利用麦克斯韦模型模拟的冰川在气温影响下的应力变化可以解释观测到的冰震日变性:当气温下降,冰川温度下降,冰体积收缩并产生应变,相应的拉张应力使得冰裂隙破裂而产生短周期冰震信号。     

长牡蛎细胞周期调控关键基因cyclin B3 的克隆及其在性腺发育中的作用

首次在长牡蛎（Crassostrea gigas）中克隆得到细胞周期蛋白B3（cyclin B3）的cDNA 全长序列和基因组结构序列。cyclin B3 基因cDNA 全长2383 bp, 其中编码区长度为1293 bp, 编码一条含430 个氨基酸的多肽链, 氨基酸序列比对和结构域分析均表明其为其他物种cyclin...