海洋与气候学视域下中北太平洋过渡区研究现状、启示与对策          下载免费PDF全文

齐庆华  靖春生 《海洋开发与管理》2023,40(5):17-26

中北太平洋过渡区是高低纬海洋西边界强化动力系统的接续区和交汇区,是大尺度和中小尺度海洋过程的突出集中区,是研究海洋和海气系统多尺度过程与海洋气候和环境生态效应的关键区。文章从海洋学和气候学角度简述中北太平洋过渡区相关海域有关科学研究成果,并就相关科学问题研究现状和不足提出启发性研究对策和建议。结果表明,中北太平洋过渡区对认识全球变暖背景下海洋与气候变化的临界条件、临界状态、跨界触发、通道机制等研究具有重要参考价值,建议通过国际合作主导引领相关地区海洋自主或联合调查,系统构建气候变化观测体系,发展多尺度过程互馈机制和可预测性研究,创建仿生仿真多功能耦合模型,突破致害致灾风险预评估与区划技术关键,为深化海洋与气候变化认识,防灾减灾研究,海洋区域治理和海洋环境与生态安全保障提供坚实的科技支撑。  相似文献   

弧后盆地玄武岩的成分变化及其成因     

俞恂  陈立辉 《岩石学报》2020,36(7):1953-1972

弧后盆地玄武岩(BABB)是弧后盆地扩张过程中岩浆作用的主要产物,其地球化学组成是认识弧后盆地演化的关键。现今弧后盆地主要集中在西太平洋地区。本文总结了该地区弧后盆地玄武岩的元素地球化学和同位素组成特征。总体而言,相对于开阔大洋洋中脊玄武岩(MORB),弧后盆地玄武岩的主量元素成分变化范围很大,在Al_2O_3-Mg O、Ti O_2-Mg O相关图上偏离了MORB的演化趋势,在Mg O相同的情况下表现出更高的Al_2O_3含量和更低的Ti O_2含量。弧后盆地玄武岩的微量元素特征一般介于MORB和弧玄武岩之间。一方面,它们与MORB一样在中、重稀土元素之间没有明显分馏;另一方面,与弧玄武岩一样富集大离子亲石元素Rb、Ba、Th、U、K,具有Pb的正异常和Nb、Ta的负异常等。其中,劳海盆、日本海海盆和冲绳海槽有部分样品具有Nb、Ta的正异常,表现出类似于E-MORB的微量元素特征。西太平洋地区弧后盆地玄武岩的Sr-Nd-Pb同位素组成变化范围较大,相对于MORB,其富集组分更常见,总体介于亏损地幔端元(DMM)、1型富集地幔(EM1)和2型富集地幔(EM2)三者之间。不同基底属性(大陆基底和大洋基底)和不同阶段的弧后盆地玄武岩的地球化学组成也有明显区别。弧后盆地玄武岩地球化学成分上的多样性主要受控于源区(地幔楔)的物质组成、熔融程度和岩浆上升过程中的变化等因素。地幔源区的不均一性主要体现在地幔楔自身的化学性质和俯冲板片的物质贡献差异。部分弧后盆地玄武岩具有异常高的地幔潜能温度、高的3He/4He比值以及E-MORB型的微量元素特征,说明其地幔源区还可能受到了地幔柱的影响。地幔潜能温度越高,俯冲流体贡献越多,地幔楔的熔融程度越大。此外,岩浆上升过程中发生的地壳混染、岩石圈中的熔体-岩石反应以及矿物的结晶分离都会改造岩浆的成分。  相似文献   

The ecology of benthic foraminifera across the Frisian Front, southern North Sea   总被引：1，自引：0，他引：1  

L.J. de Nooijer  I.A.P. Duijnstee  M.J.N. Bergman  G.J. van der Zwaan   《Estuarine, Coastal and Shelf Science》2008,78(4):715-726

Benthic foraminifera were collected across the Frisian Front, a biologically enriched transition-zone with high organic matter content below a tidal-mixing front in the southern North Sea. On four occasions between 2002 and 2005, box-cores from different hydrographic regimes (i.e. tidally mixed, frontal and stratified) at depths between 30- and 45-m deep were sampled. The results indicate that standing stocks and foraminiferal diversity are higher in the central zone of the Frisian Front than further away from the frontal zone. Most of the abundant species occupy a specific zone relative to the front's central position. Elphidium excavatum is abundant at the southern edge of the Frisian Front, where input of labile organic matter is high and physical disturbance (i.e. resuspension of fine-grained material) is relatively frequent. Ammonia tepida and Quinqueloculina spp. dominate at the front's center where organic carbon input is relatively high. Hopkinsina pacifica has its highest abundances at the deepest, northerly boundary of the front, and Eggerella scabra dominates the deeper, seasonally stratified Oyster Grounds north of the front. Differences in seasonal distribution patterns were minor compared to spatial patterns. Depth distributions varied between summer (more ‘epifaunal’ distribution) and winter (vertically more evenly distributed). The latter suggests that the vertical distribution of foraminifera is governed by the arrival of fresh organic matter at the seafloor in spring and summer. A comparison with foraminiferal abundances across the Frisian Front in 1988/1989 reveals that total abundances and distribution of the most abundant species were similar in both data sets, despite a macrobenthic regime shift at the Frisian Front in the early 1990s. The decoupled dynamics of foraminifera and macrofauna suggests that foraminifera reflect reliably the hydrodynamic environment (stratified, frontal, mixed), despite the changed macrofaunal community and its physical and geochemical consequences.  相似文献   

Photosynthetic community responses to upwelling in mesoscale eddies in the subtropical North Atlantic and Pacific Oceans   总被引：1，自引：0，他引：1  

Thomas S. Bibby  Maxim Y. Gorbunov  Kevin W. Wyman  Paul G. Falkowski   《Deep Sea Research Part II: Topical Studies in Oceanography》2008,55(10-13):1310

In this paper we summarise the photo-physiological responses of phytoplankton to upwelling of macronutrients in mesoscale eddies in the subtropical North Atlantic (EDDIES project, Sargasso Sea) and subtropical North Pacific (E-FLUX project, Hawaii). The observations, obtained on two sets of cruises over 2 years, occupied six cyclonic eddies and two mode-water eddies. The photosynthetic physiological parameters were measured using a bench-top fluorescence induction and relaxation (FIRe) system and a submersible in situ fast repetition rate fluorometer (FRRF) deployed on an undulating towed vehicle. Both of these instruments were used to provide highly sensitive and well-resolved data on community responses. The responses are dependent on both the type of eddy and its stage of development. Our results indicate that, while cyclonic eddies in the Atlantic and Pacific can increase primary photosynthetic production early in their development, mode-water eddies in the subtropical North Atlantic can support patchy blooms of large diatoms for long periods of time (more than 3 months).  相似文献   

Characteristics of thermal finestructure in the southern Yellow Sea and the East China Sea from airborne expendable bathythermograph measurements     

Sunghyea Park  Peter C. Chu 《Journal of Oceanography》2008,64(6):859-875

Four surveys of airborne expendable bathythermograph with horizontal spacing of about 35 km and vertical spacing of 1 m extending from the surface down to 400 m deep are used to analyze thermal finestructures and their seasonality in frontal zones of the southern Yellow Sea and the East China Sea. Finestructure characteristics are different not only among fronts but also along the same front, implying different mixing mechanisms. Summer thermocline intrusions with thickness from few to 40 meters, generated by the vertically-sheared advection, are identified along the southern tongue of the Cheju-Yangtze Front (especially south of Cheju Island). The finestructures south of the Yangtze Bank (i.e. the western tip of the southern tongue) produced by strong along-frontal currents are not as rich as elsewhere in the southern tongue. The Cheju-Tsushima Front presents mixed finestructures due to confluent currents from various origins. The irregular-staircase finestructures in the Kuroshio region (below the seasonal thermocline), driven by double-diffusive mixing, show seasonal invariance and vertical/horizontal coherence. The strength of mixing related to finestructure is weaker in the Kuroshio region than in the Cheju-Tsushima Front or south of Cheju Island. The profiles in the Tsushima Warm Current branching area show large (∼50 m thick), irregular-staircase structures at the upper 230 m depth, which coincides roughly with the lower boundary of the maximum salinity layer. The finestructure at depths deeper 230 m is similar to that in the Kuroshio region. The possible mechanisms for generating the finestructures are also discussed.  相似文献   

Influence of the Columbia River plume (USA) on the vertical and horizontal distribution of mesozooplankton over the Washington and Oregon shelf     

Peterson  Jay O.; Peterson  William T. 《ICES Journal of Marine Science》2008,65(3):477-483

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Thermal lenses and internal solitons in Chapala Lake, Mexico     

Filonov  A. E.  Tereshchenko  I. E. 《中国海洋湖沼学报》1999,17(4):308-314

INTRODUCTIONThelargestlakeinMexicoandthirdlargestinLatinAmerica,ChapalaLake(approximately2 0°N) ,is 1 50 0mabovesealevel,measures 75× 2 5km ,hasaveragedepthof6m (maximumdepthcloseto 1 1m)andamountainchainalongitsnorthernandsouthernshores (Fig .1a) .TheLermaRiverflowsintoit;theSantiagoRiverflowsoutofit.Thebeautifullandscape,andwarmclimateconducivetobreezecirculationalongitsshore ;absenceofabrupttemperaturevariations,andthemoderateairhumidityat tractmanytouriststothelake .Manyretirees…  相似文献   

Crustal structure of the deepwater west Niger Delta passive margin from the interpretation of seismic reflection data     

Sepribo Eugene Briggs  Joe Cartwright  Richard J. Davies 《Marine and Petroleum Geology》2009

The interpretation of 2D and 3D seismic reflection data complemented with gravity data allows the crustal architecture of the deepwater west Niger Delta passive margin to be defined. The data show that the area is underlain by oceanic crust that is characterised by a thickness of 5–7 km and by internal reflectivity consisting of both dipping and sub-horizontal reflectors. Some of the dipping reflections can be traced up to the top of the basement where they offset it across a series of minor to major thrust faults. Other internal reflections are attributed to extensional shear zones and possibly due to intrusions in the lower crust. The Moho can be correlated as a discrete reflection over >70% of the study area. It is generally smooth, but localised relief of up to 1 km is observed. The southeastern part of the study area is dominated by a zone of SW–NE striking basement thrusts.  相似文献   

Ichthyoplankton spatial pattern in the inner shelf off Bahía Blanca Estuary, SW Atlantic Ocean     

Mnica Susana Hoffmeyer  Menndez María Clara  Biancalana Florencia  Nizovoy Alicia Mabel  Torres Eduardo Ramn 《Estuarine, Coastal and Shelf Science》2009,84(3):181-392

This study focuses on the composition, abundance and distribution of ichthyoplankton in the inner shelf area off Bahía Blanca Estuary on the SW Atlantic Ocean during late spring. Eggs and larvae of Brevoortia aurea, Engraulis anchoita, Parona signata, Sciaenidae spp. – such as Cynoscion guatucupa and Micropogonias furnieri –, and Odontesthes argentinensis were found. Species richness was low probably as a result of season and shallow depths. Ichthyoplankton abundance reached values close to 10 000 per 10 m⁻³ (eggs) and 4000 per 10 m⁻³ (larvae) and displayed a spatial distribution pattern with maximum abundance values restricted to a band parallel to the coast. Differences between egg and larval patterns, probably derived from a different displacement and hydrodynamic behavior, were observed. Egg and larvae distribution patterns were found related with spawning areas and to directly depend on salinity and mesozooplankton. The larvae distribution pattern, in particular, was found to inversely depend on particulate organic carbon. In addition, the geographic location of egg and larvae maxima strongly coincided with a saline front reported for this area in springtime, thus suggesting a direct relationship with it.  相似文献   

两种不同类型大陆边缘的初步研究   总被引：2，自引：0，他引：2  

王述功  刘忠臣  吴金龙 《海洋与湖沼》1996,27(6):577-583

１９８６年１０月－１９８７年５月,中国第三次南极考察暨首次环球科学考察的实测重力资料表明,太平洋型活动陆缘重力异常面貌复杂,空间异常变化剧烈,处于极度不均衡状太民。用ｓｉｎｘ／ｘ法反演了 莫氏面深度,利用水层和地壳引起的垂直引力之和与实测的空间异常之差反演了软流层顶界的深度。  相似文献