中国地磁台观测的2014年地磁急变

地磁急变（jerk）是起源于地球外核并在导电地幔过滤效应后在地球表面观测到的一种地磁现象,其反映了地核内部某些动力学过程.Jerks在空间范围上既可以是区域性的,也可以是全球性的.中国地区地磁台能否检测到2014年jerk？针对这一问题,利用中国大陆10个地磁台的磁静日月均值和CHAOS-6全球磁场模型,分析了X、Y和Z分量2008—2018年期间的长期变化,估算了2014年前、后的长期加速度值,确定了2014年地磁jerk的时间和强度.研究表明中国地磁台Y分量的长期变化为"Λ"型,Z分量存在明显的"V"型,具有典型的jerk特点.Y分量jerk出现的时间大约在2014年6月,比非洲大陆的Algeria TAM台和南美洲French Guiana KOU台时间滞后大约4个月.这暗示着产生jerks的地核流体波动的时序特点.中国西部和东北部地磁台的长期变化形态有明显的差别,主要由非偶极磁场引起.CHAOS-6模型与地面台站的长期变化形态并非始终一致.本文结果有助于更好地理解和解释长期变化的时间演变和地理分布,并为深入探讨jerks的地核起源和驱动机制提供新的观测约束.     

黄渤海海水中丙烯酸的生成与降解的初步研究

在黄渤海海域对β-二甲基巯基丙酸内盐（DMSP）降解产生丙烯酸和丙烯酸的降解过程做了初步研究。结果表明,海水中有明显的DMSP降解和丙烯酸的生成现象。在DMSP降解初期,DMSP不断降解,丙烯酸则在经过1 h后浓度开始上升,达到最大值后再次下降。起始DMSP浓度越高,降解得越完全,且丙烯酸最大值越大。在观测的5 h内,丙烯酸的表观降解速率总是大于DMSP的表观降解速率,且两者都与初始浓度成正相关。在丙烯酸的降解过程中,黑暗条件下起始浓度越大,丙烯酸变化速率越大,而光照条件下则恰好相反。光化学反应中前2 h表现为丙烯酸的光化学生成,而后2 h表现为光化学降解。     

Dissolved organic matter and its role in red tide succession in the East China Sea in spring

Dissolved fluorescent organic matter was measured using fluorescence excitation-emission matrix spectroscopy at three temporal points during a Synechococcus bloom after diatom bloom dispersion in spring, 2007. Carbohydrate and dissolved organic carbon were also analyzed. The relationship between organic matter and red tide succession was examined. The results show that after the diatom bloom, tyrosine-like fluorescence B intensity was very high within the water column and exhibited a negative correlation wi...     

An Analysis of the Coastal Fish Assemblage of the Ustica Island Marine Reserve (Mediterranean Sea)

A study of the coastal fish assemblages in the marine park of Ustica Island (Southern Tyrrhenian Sea, Mediterranean) was conducted from June 1994 to September 1995 and from June 1996 to September 1997. The principal aims of the research were to: (1) define the faunistic features of local fish communities; (2) assess the effectiveness of the protection regime of the marine park on the fish assemblages ('reserve effect'); (3) provide information on the distribution of some Epinephelus and Diplodus species in the shallowest depth zone of the island. During seasonal surveys, underwater visual censuses were carried out at several sites located in three zones of the island, each with a different level of protection. Observations were made along 250 m² transects at 3–5, 10–15 and 25–30 m depth ranges. Additional surveys were made by SCUBA diving and snorkelling. A statistically significant effect of depth on the fish community parameters was observed, whereas differences linked to protection level, zones, sites and seasons were not significant. The abundance and frequency of occurrence of some species, particularly dusky grouper Epinephelus marginatus , were positively correlated with the degree of protection of the different zones of the marine park. Certain sites of the island are important as nursery areas for three species of the genus Diplodus ( i.e., D. puntazzo, D. sargus and D. vulgaris ).     

Expression of putative zinc-finger protein lcn61 gene in lymphocystis disease virus China （LCDV-cn） genome

An open reading frame (lcn61) of lymphocystis disease virus China (LCDV-cn), probably responsible for encoding putative zinc-finger proteins was amplified and inserted into pET24a (+) vector. Then it expressed in E. coli BL21 (DE3), and His-tag fusion protein of high yield was obtained. It was found that the fusion protein existed in E. coli mainly as inclusion bodies. The bioinformatics analysis indicates that LCN61 is C2H2 type zinc-finger protein containing four C2H2 zinc-finger motifs. This work provides a theory for functional research of lcn61 gene. Supported by High Technology Research and Development Program of China (863 Program, No. 2006AA100309)     

末次冰消期以来东海内陆架沉积物磁化率的环境意义

对末次冰消期以来东海内陆架沉积物磁化率的影响因素及其蕴含的古环境信息进行了探讨.对位于浙闽沿岸泥质沉积中心附近的EC2005孔沉积物磁化率、岩性、粒度、常量元素、矿物以及AMS<'14>C测年数据进行了综合分析,得出以下主要结论:EC2005孔沉积物磁化率的变化受多种因素的制约,不同层位的主要控制因素不同,60.20～...     

东海中南部秋季游泳动物多样性及群落结构

根据2018年11月东海中南部游泳动物底拖网调查数据,对该海域游泳动物种类组成、优势种、种类多样性及群落结构进行研究。结果表明,调查共捕获游泳动物181种,其中鱼类133种,甲壳类34种,头足类14种;优势种（IRI≥500）为七星底灯鱼（Benthosema pterotum）、带鱼（Trichiurus lepturus）、麦氏犀鳕（Bregmaceros mcclellandi）、龙头鱼（Harpadon nehereus）和日本发光鲷（Acropoma japonicum）。多样性指数结果显示,东海中南部海域丰度（d）的变化范围为0.37～5.94,种类多样性指数（H′）的变化范围为0.38～2.64,均匀度（J）的变化范围为0.14～0.71。根据聚类分析结果将东海中南部海域游泳动物群落分为以90 m等深线为界的两个群组,群组间的差异主要由七星底灯鱼、镰鲳（Pampus echinogaster）、龙头鱼、黄鲫（Setipinna tenuifilis）、麦氏犀鳕等引起。BIOENV结果显示水深与游泳动物群落结构相关性最密切（r_w=0.55）。本研究结果可为类似海域游泳动物种类多样性和群落结构的研究提供参考,也可为研究海域渔业资源开发、利用与养护等政策的制定提供科学依据。     

Tracking the last sea-level cycle: seafloor morphology and shallow stratigraphy of the latest Quaternary New Jersey middle continental shelf

Seafloor geomorphology and surficial stratigraphy of the New Jersey middle continental shelf provide a detailed record of sea-level change during the last advance and retreat of the Laurentide ice sheet (120 kyr B.P. to Present). A NW–SE-oriented corridor on the middle shelf between water depths of 40 m (the mid-shelf “paleo-shore”) and 100 m (the Franklin “paleo-shore”) encompasses 500 line-km of 2D Huntec boomer profiles (500–3500 Hz), an embedded 4.6 km² 3D volume, and a 490 km² swath bathymetry map. We use these data to develop a relative stratigraphy. Core samples from published studies also provide some chronological and sedimentological constraints on the upper <5 m of the stratigraphic succession.The following stratigraphic units and surfaces occur (from bottom to top): (1) “R”, a high-amplitude reflection that separates sediment >46.5 kyr old (by AMS ¹⁴C dating) from overlying sediment wedges; (2) the outer shelf wedge, a marine unit up to 50 m thick that onlaps “R”; (3) “Channels”, a reflection sub-parallel to the seafloor that incises “R”, and appears as a dendritic system of channels in map view; (4) “Channels” fill, the upper portion of which is sampled and known to represent deepening-upward marine sediments 12.3 kyr in age; (5) the “T” horizon, a seismically discontinuous surface that caps “Channels” fill; (6) oblique ridge deposits, coarse-grained shelly units comprised of km-scale, shallow shelf bedforms; and (7) ribbon-floored swales, bathymetric depressions parallel to modern shelf currents that truncate the oblique ridges and cut into surficial deposits.We interpret this succession of features in light of a global eustatic sea-level curve and the consequent migration of the coastline across the middle shelf during the last 120 kyr. The morphology of the New Jersey middle shelf shows a discrete sequence of stratigraphic elements, and reflects the pulsed episodicity of the last sea-level cycle. “R” is a complicated marine/non-marine erosional surface formed during the last regression, while the outer shelf wedge represents a shelf wedge emplaced during a minor glacial retreat before maximum Wisconsin lowstand (i.e., marine oxygen isotope stage 3.1). “Channels” is a widespread fluvial subarial erosion surface formed at the late Wisconsin glacial maximum 22 kyr B.P. The shoreline migrated back across the mid-shelf corridor non-uniformly during the period represented by “Channels” fill. Oblique ridges are relict features on the New Jersey middle shelf, while the ribbon-floored swales represent modern shelf erosion. There is no systematic relationship between modern seafloor morphology and the very shallowly buried stratigraphic succession.     

Current and thermohaline characteristics of the Arabian Sea during January 1998

Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area.     

The eastern extent of the Barents–Kara ice sheet during the Last Glacial Maximum based on seismic-reflection data from the eastern Kara Sea

We present sub-bottom profiling (sparker and Parasound) results from the eastern Kara Sea, on the Eurasian Arctic margin, which enable the identification of the Last Glacial Maximum (LGM) ice extent. The analysed profiles show that glacigenic diamicton is ubiquitous at the seafloor, east of about 95°E and 78°N. The eastern margin of this diamicton is expressed in a conspicuous morainic ridge at the entrance to the Vilkitsky Strait, and to the south the diamicton projection aligns with the LGM limit mapped at the north-western Taymyr. The bottom of the Voronin Trough further north is also covered with diamicton and has numerous erosional bedforms, indicating a streamlined flow of grounded ice along the trough. Accurate dating of the diamicton is not attainable, but the correlation of pre-diamict sediments to well-dated sections in the Laptev Sea, and available ¹⁴C ages from sediments on top of the diamicton, indicate its LGM age. These results support the palaeogeographic reconstruction that assumes the extension of the LGM Barents–Kara ice sheet as far east as Taymyr. This configuration implies that LGM ice blocked the drainage of the Ob and Yenisey rivers on the Kara shelf. This inference is consistent with the presence of large (>100 km wide) lenses of basin infill adjacent to the southern margin of the diamicton. However, the limited distribution of the eastern Kara ice lobe, not extending on Severnaya Zemlya, suggests that the ice was fairly thin and short-lived: insufficient for the accumulation of the gigantic proglacial lakes that occurred during earlier glaciations.