南海深海平原柱状样QD189磁化率、非磁滞剩磁、粒度、碎屑矿物丰度之间的主要关系

磁学可能是南海深海平原古环境研究取得突破的关键方面之一。众多磁学参数中,磁化率是最基本、最综合反映沉积物磁性矿物总体状况的参数,非磁滞剩磁对单畴颗粒含量敏感,而且单畴颗粒是剩磁的主要携带者,结合粒度、碎屑矿物丰度等数据探索南海深海平原柱状样QD189磁化率和非磁滞剩磁地质含义。在磁化率大于45×10-5层位和481 cm以浅的磁化率小于45×10-5的层段,磁化率、2~5粒级含量、ARM和ARM@20m T变化一致性较好,2~5粒级软磁性多畴颗粒含量变化可能是这些层位磁化率变化的主要原因。在808~488 cm层段内,小于45×10-5的磁化率与2~5粒级含量、ARM和ARM@20m T变化总体上一致性较差,磁化率变化机制有待进一步研究。2~5粒级是QD189重要的较粗粒级组分,大体上以深度350 cm为界具有下层段含量较高且粒度变化大、上层段含量较低且粒度变化小的特点。ARM@20m T比ARM更加真实地表示QD189单畴颗粒含量,除了单畴颗粒外,9~12粒级假单畴、多畴颗粒矿物对665~48 cm层段的ARM可能有一定贡献,其中,层段548~310 cm的ARM中可能还有6~9粒级多畴颗粒的贡献。通过碎屑矿物丰度、火山玻璃丰度和（或）磁化率异常峰值的对应关系识别出6次火山活动,火山玻璃丰度的分布特点还揭示出QD189中普遍发生生物扰动作用。

南海深海环流研究进展

深海科学是全球气候变化研究的重要组成部分,孕育着科学上的重大突破和发现,是海洋科学研究的重要领域.近些年来,随着我国对深海科学研究的逐步深入,南海深海环流研究越来越引起海洋科学家的关注,并已取得若干研究成果.本文将从南海深海环流观测出发,首先总结近年来南海深海环流观测方面研究工作,然后介绍南海深海环流未来研究初步设想.

南海深海塑料垃圾污染

渔业捕捞及商业航运活动的塑料排放是南海深海塑料污染的主要来源。南海深海微塑料污染始于20世纪80年代,具有明显陆源输入的特征,陆架近岸区域微塑料污染严重。陆坡深海峡谷是塑料/微塑料向深海盆地输运的主要通道,近底浊流在输运中发挥了重要作用。综述了南海海底塑料垃圾深潜研究的最新进展,首次提出了深海塑料垃圾生态系统的概念。

Seismic stratigraphy of the Qiongdongnan deep sea channel system,northwest South China Sea

Based on more than 4000 km 2D seismic data and seismic stratigraphic analysis, we discussed the extent and formation mechanism of the Qiongdongnan deep sea channel. The Qiongdongnan deep sea channel is a large incised channel which extends from the east boundary of the Yinggehai Basin, through the whole Qiongdongnan and the Xisha trough, and terminates in the western part of the northwest subbasin of South China Sea. It is more than 570 km long and 4–8 km wide. The chaotic (or continuous) middle (or high) amplitude, middle (or high) continuity seismic facies of the channel reflect the different lithological distribution of the channel. The channel formed as a complex result of global sea level drop during early Pliocene, large scale of sediment supply to the Yinggehai Basin, inversion event of the Red River strike-slip fault, and tilted direction of the Qiongdongnan Basin. The large scale of sediment supply from Red River caused the shelf break of the Yinggehai Basin to move torwards the S and SE direction and developed large scale of prograding wedge from the Miocene, and the inversion of the Red River strike-slip fault induced the sediment slump which formed the Qiongdongnan deep sea channel.

Accumulation and exploration of gas hydrate in deep-sea sediments of northern South China Sea

The large deep-sea area from the southwestern Qiongdongnan Basin to the eastern Dongsha Islands,within the continental margin of northern South China Sea,is a frontier of natural gas hydrate exploration in China.Multiform of deep-sea sedimentations have been occurred since late Miocene,and sediment waves as a potential quality reservoir of natural gas hydrate is an most important style of them.Based on abundant available data of seismic,gravity sampling and drilling core,we analyzed the characteristics of seismic reflection and sedimentation of sediment waves and the occurrence of natural gas hydrate hosted in it,and discussed the control factors on natural gas hydrate accumulation.The former findings revealed the deep sea of the northern South China Sea have superior geological conditions on natural gas hydrate accumulation.Therefore,it will be of great significance in deep-sea natural gas hydrate exploration with the study on the relationship between deep-sea sedimentation and natural gas hydrate accumulation.

A new method for the estimation of oceanic mixed-layer depth using shipboard X-band radar images

Shipboard X-band radar images acquired on 24 June 2009 are used to study nonlinear internal wave characteristics in the northeastern South China Sea.The studied images show three nonlinear internal waves in a packet.A method based on the Radon Transform technique is introduced to calculate internal wave parameters such as the direction of propagation and internal wave velocity from backscatter images.Assuming that the ocean is a two-layer finite depth system,we can derive the mixed-layer depth by applying the internal wave velocity to the mixed-layer depth formula.Results show reasonably good agreement with in-situ thermistor chain and conductivity-temperature-depth data sets.

Characteristics of water exchange in the Luzon Strait during September 2006

The Luzon Strait is the only deep channel that connects the South China Sea(SCS) with the Pacific.The transport through the Luzon Strait is an important process influencing the circulation,heat and water budgets of the SCS.Early observations have suggested that water enters the SCS in winter but water inflow or outflow in summer is quite controversial.On the basis of hydrographic measurements from CTD along 120° E in the Luzon Strait during the period from September 18 to 20 in 2006,the characteristics of temperature,salinity and density distributions are analyzed.The velocity and volume transport through the Luzon Strait are calculated using the method of dynamic calculation.The major observed results show that water exchanges are mainly from the Pacific to the South China Sea in the upper layer,and the flow is relatively weak and eastward in the deeper layer.The net volume transport of the Luzon Strait during the observation period is westward,amounts to about 3.25 Sv.This result is consistent with historical observations.

Recovery of Bathymetry from Altimeter Data

At present,there exist two methods used to recover the bathymetry from altimeter data,i.e.the deterministic method and the stochastic method.In this paper,the principles of the two methods are introduced first.Then according to the theory of least_square collocation,a modified statistical model for recovering bathymetry from altimeter data is proposed.The new model has been used for computing the ocean depth in the South China Sea from altimeter_derived gravity anomalies.Finally the predicted depths are compared with the ship_borne depth.It shows that they agree with each other very well.

Diatom assemblages in surface sediments from the South China Sea as environmental indicators

We studied diatom distribution from 62 samples from the uppermost 1 cm of sedimem in the South China Sea （SCS）, using grabs or box corers in three cruises between 2001-2007. Fifty six genera, 256 species and their varieties were identified. Dominating species included Coscinodiscus africanus, Coscinodiscus nodulifer, Cyclotella stylorum, Hemidiscus cuneiformis, Melosira sulcata, Nitzschia marina, Roperia tesselata, Thalassionema nitzschioides, Thalassiosira excentrica, and Thalassiothrix longissima. Most surface sediments in the SCS were rich ill diatoms, except for a few coarse samples. Average diatom abundance in the study area was 104 607 valve/g. In terms of the abundance, ecology, and spatial distribution, seven diatom zones （Zones 1-7） were recognized. Zone 1 （northern continental shelf） is affected by warm currents, SCS northern branch of the Kuroshio, and northern coastal currents; Zone 2 （northwestern continental shelf） is affected by intense coastal currents; Zone 3 （Xisha Islands sea area） is a bathyal environment with transitional water masses; Zone 4 （sea basin） is a bathyal-to-deep sea with stable and uniform central water masses in a semi-enclosed marginal sea; Zone 5 （Nansba Islands marine area） is a pelagic environment with relatively high surface temperature; Zone 6 （northern Sunda Shelf） is a tropical shelf environment; and Zone 7 （northern Kalimantan Island shelf area） is affected by warm waters from the Indian Ocean and coastal waters. The data indicate that these diatom zones are closely related to topography, hydrodynamics, temperature, nutrients and especially the salinity. Better understanding of the relationship between diatom distribution and the oceanographic factors would help in the reconstruction of the SCS in the past.

南海深层环流与经向翻转环流的研究进展

吕宋海峡"深水瀑布"一方面驱动了南海深层气旋式环流,另一方面入侵的北太平洋深层水在南海内区通过混合变性并上升.这两个过程极大地贡献了南海经向翻转环流.同时无论是南海深层水平环流,还是经向翻转环流,均受到南海内区复杂地形的调制,而南海经向翻转环流的空间结构又在一定程度上体现了南海深层环流与中、上层环流的联系.本文回顾了近年来南海深层环流与经向翻转环流的研究,总结了南海深海环流的驱动机制及其地形的调控、南海经向翻转环流的空间结构及其成因.

Bathymetric Inversion of South China Sea from Satellite Altimetry Data

This paper focuses on the study of ocean bathymetric inversion from satellite altimeter data by using FFT technique.In this study,the freeair gravity anomalies over the South China Sea are determined by the satellite altimeter data of GEOSAT,ERS1,ERS2 and T/P.And the 2.5′×2.5′ bathymetry model in South China Sea is calculated from the gravity anomalies with the inversion model given.After the analysis of the inversion and the comparison between the results,some conclusions can be drawn.

What Depth Should Deep-Sea Water be Pumped up from in the South China Sea for Medicinal Research?

In this study, seawater was pumped up from 150, 200, 300, 500 and 1000 m in the South China Sea and analyzed to make certain what depth should deep-sea water (DSW) be pumped up for medicinal usage. The pumping depth of DSW was determined on the basis of chemical ingredients. The analyses of inorganic elements and dissolved organic matter (DOM) were performed by inductively coupled plasma mass spectrometry (ICP-MS) and ultra performance liquid chromatography-mass spectrometry (UPLC-MS) respectively. The raw data were used for hierarchical cluster analysis (HCA) and principal component analysis (PCA). The results showed that seawater pumped up from 500 m and 1000 m was similar in their chemical ingredients, and was different from the seawater pumped up from other depths. These results indicated that seawater from more than 500 m depth had relatively stable chemical ingredients and could be used as DSW in the South China Sea.

Spatiotemporal variations of deep-sea sediment components and their fluxes since the last glaciation in the northern South China Sea

Sediment components and their fluxes of Cores MD12-3428(water depth: 903 m), MD12-3433(water depth: 2125 m),and MD12-3434(water depth: 2995 m), obtained along a transect on the continental slope of the northern South China Sea, have been conducted to reveal the spatiotemporal variations and the controlling factors of the sediment components and of their fluxes.Results show that deep-sea sediments in the northern South China Sea are composed mainly of terrigenous(59–89%) and carbonate(6–38%) particles, with minor components of opal(1.6–9.4%) and organic matter(0.7–1.9%). Fluxes of terrigenous and carbonate particles reach up to 2.4–21.8 and 0.4–6.5 g cm–2 kyr–1, respectively, values that are one to two orders of magnitude higher than the fluxes of opal and organic matter. Temporal variations of the percentages and fluxes of deep-sea sediment components have displayed clear glacial-interglacial cyclicity since the last glaciation. Terrigenous, opal, and organic matter percentages and their fluxes increas clearly during marine isotope stage 2, while carbonate percentages and fluxes show an opposite variation pattern or are characterized by an unremarkable increase. This implies that deep-sea carbonate in the South China Sea is affected by the dilution of terrigenous inputs during the sea-level lowstand. With increasing water depth along the transect, the terrigenous percentage increases but with largely decreased fluxes. Both the percentage and flux of carbonate decrease, while the percentages and fluxes of opal and organic matter display much more complicated variational features. The spatiotemporal variations of deep-sea sediment components and of their fluxes since the last glaciation in the northern South China Sea are strongly controlled by sea-level fluctuations. Simultaneously, terrigenous supply associated with monsoonal rainfall, marine primary productivity,and the dilution effect between terrigenous and biogenic particles, also play interconnected roles in the sediment accumulation processes.