西菲律宾海比科尔陆架深海沉积物古菌多样性研究

通过构建16S rRNA 基因文库, 对西太平洋西菲律宾海东板比科尔陆架5 个不同层位沉积物样品中的古菌的多样性进行了研究, 并获得了465 个有效克隆63 个OTUs （Operational Taxonomic Units）。通过16S rRNA 序列与GenBank 已知序列的同源性比较及构建系统进化树的结果显示...     

中西太平洋金枪鱼延绳钓渔获组成及其多样性分析

根据2009年6～11月金枪鱼延绳钓观察员海上采集的数据,对中西太平洋S2°05′～S7°51′,W159°48′～W168°10′海域的延绳钓渔获物组成进行了分析.126个站点(钩次)的种类组成分析表明,该作业区域的渔获物有鱼类35种,隶属于9目22科30属;鲸类2种,隶属于1目2科2属;龟鳖类1种.反映种类组成多样...     

黄海绿潮应急溯源数值模拟初步研究

基于三维全动力POM 海洋模式, 根据2008 年6 月1 日海监飞机监测绿潮所在位置, 采用拉格朗日粒子追踪法反向积分, 追溯绿潮来源。数值模拟结果显示, 回溯至5 月中旬, 绿潮主要来源于黄海南部江苏连云港和盐城近海海域。黄海绿潮溯源数值模拟, 为政府相关部门了解绿潮的源头, 并采取相应的措施提供依据, 进而为保护生态环境、防灾减灾做贡献。     

印度洋热含量在南海夏季风爆发中的作用

利用Scripps海洋研究所0—400m上层海洋热含量资料和美国环境监测中心/国家大气研究中心(National Centers for Environmental Prediction/National Center for Atmospheric Research,NCEP/NCAR)的再分析资料,运用经验正交分解(empirical orthogonal function,EOF)等统计方法,研究在有ENSO影响和去除ENSO影响的情况下,前期春季印度洋热含量如何影响南海夏季风爆发。结果表明,在没有扣除ENSO信号的情况下,热带印度洋热含量EOF分解第一模态呈东西相反变化的空间分布。印度洋东部热含量为正(负)异常、西部为负(正)异常时,南海夏季风爆发较早(晚),印度洋上层热含量主要通过影响热带印度洋上空大气的垂直运动和高低层辐散辐合,进而影响季风纬向环流的强弱,来影响南海夏季风爆发的早晚。在扣除ENSO信号的情况下,印度洋热含量CEOF(conditional EOF)第一模态的空间分布类似于EOF第一模态的空间分布;第二模态表现为除小部分海区外,热带印度洋热含量呈一致变化的海盆模态。这两个模态对南海夏...     

若干西边界潜流的气候态分布特征

"西边界潜流(WBUC)"是海洋环流中的重要现象,与表层环流相比,对次表层潜流的结构认识不足。本文利用SODA、OFES和ARGO资料,分析了北太平洋中的棉兰老潜流(MUC)和吕宋潜流(LUC)、南太平洋中的大堡礁潜流(GBRUC)和东澳大利亚潜流(EAUC)及南印度洋中的阿加勒斯潜流(AUC)的气候态空间分布特征,并且根据地转流反向的判据,分析WBUC的发生条件。     

Microfacies and diagenesis of older Pleistocene (pre‐last glacial maximum) reef deposits,Great Barrier Reef,Australia (IODP Expedition 325): A quantitative approach

During Integrated Ocean Drilling Program Expedition 325, 34 holes were drilled along five transects in front of the Great Barrier Reef of Australia, penetrating some 700 m of late Pleistocene reef deposits (post‐glacial; largely 20 to 10 kyr bp ) in water depths of 42 to 127 m. In seven holes, drilled in water depths of 42 to 92 m on three transects, older Pleistocene (older than last glacial maximum, >20 kyr bp ) reef deposits were recovered from lower core sections. In this study, facies, diagenetic features, mineralogy and stable isotope geochemistry of 100 samples from six of the latter holes were investigated and quantified. Lithologies are dominated by grain‐supported textures, and were to a large part deposited in high‐energy, reef or reef slope environments. Quantitative analyses allow 11 microfacies to be defined, including mixed skeletal packstone and grainstone, mudstone‐wackestone, coral packstone, coral grainstone, coralline algal grainstone, coral‐algal packstone, coralline algal packstone, Halimeda grainstone, microbialite and caliche. Microbialites, that are common in cavities of younger, post‐glacial deposits, are rare in pre‐last glacial maximum core sections, possibly due to a lack of open framework suitable for colonization by microbes. In pre‐last glacial maximum deposits of holes M0032A and M0033A (>20 kyr bp ), marine diagenetic features are dominant; samples consist largely of aragonite and high‐magnesium calcite. Holes M0042A and M0057A, which contain the oldest rocks (>169 kyr bp ), are characterized by meteoric diagenesis and samples mostly consist of low‐magnesium calcite. Holes M0042A, M0055A and M0056A (>30 kyr bp ), and a horizon in the upper part of hole M0057A, contain both marine and meteoric diagenetic features. However, only one change from marine to meteoric pore water is recorded in contrast with the changes in diagenetic environment that might be inferred from the sea‐level history. Values of stable isotopes of oxygen and carbon are consistent with these findings. Samples from holes M0032A and M0033A reflect largely positive values (δ¹⁸O: ?1 to +1‰ and δ¹³C: +1 to +4‰), whereas those from holes M0042A and M0057A are negative (δ¹⁸O: ?4 to +2‰ and δ¹³C: ?8 to +2‰). Holes M0055A and M0056A provide intermediate values, with slightly positive δ¹³C, and negative δ¹⁸O values. The type and intensity of meteroric diagenesis appears to have been controlled both by age and depth, i.e. the time available for diagenetic alteration, and reflects the relation between reef deposition and sea‐level change.     

Characteristics of tropical cyclones making landfall on the Pacific coast of Mexico: 1970-2010

This study evaluates impacts from tropical cyclone (TC) landfalls on populated areas located along the Pacific Ocean coast of Mexico. The period of interest is from 1970 through 2010 and an international disaster database is used to identify the impact from the landfalling TCs. More than 30 landfall events occurred during the period; we examined the top 25 TCs based on rainfall accumulation, as well as the top 10 TC-related disasters based on the affected population. Each event resulted in affected population from 20 000 to more than 800 000. Strong winds and heavy rainfall, during periods of one to three days, are associated with property damage and loss of lives. Our results indicate that excessive rainfall accumulations and daily rates, over highly populated areas, are important elements associated with the occurrence of disasters. Six of the top 10 TC-related disasters occurred during El Niño and three during neutral conditions; however, looking at the top 25 events, 10 occurred during El Niño and 10 during neutral conditions. Three case studies that occurred during El Niño events (Liza in 1976, Pauline in 1997, and Lane in 2006) are documented in more detail as they affected areas with different population densities in the southern and northwestern coasts of Mexico.     

The origin of the Naturaliste Plateau,SE Indian Ocean: Implications from dredged basalts

Although a 1972 dredging by USNS Eltanin from the submarine Naturaliste Plateau was reported to yield rocks of continental origin, a re‐examination of the dredge haul shows that the rock clasts are in fact altered tholeiitic basalts. They have affinities both with MOR basalts and, especially, within‐plate basalts. Petrographically they correlate most closely with the Bunbury Tholeiitic Suite on the Australian mainland to the east. The basalts are reworked cobbles in a manganiferous Quaternary slump mass, which contains a quartz‐rich, felsic, detrital mineral suite with a granite‐gneiss provenance. The basalt cobbles were part of a basal conglomerate, which covered large areas of the Plateau. It is suggested that this was laid down from nearby elevated volcanic structures formed during the inception of seafloor spreading and the separation of Greater India from Australia at about 122 Ma BP.     

Crustal structure of the western Arafura Sea from ocean bottom seismograph data

Refraction data taken from ocean bottom seismograph recordings in the western Arafura Sea indicate a continental‐type structure for the region. This structure is characterised by a thin column (2 km) of sediments, with velocities ranging from about to 2 to 4 km s^‐1, overlying an essentially two layer crust. The compressional wave velocities in the upper and lower crust are 5.97 and 6.52 km s^‐1, respectively, with the boundary between the layers at a depth of 11 km. Very weak mantle‐refracted arrivals with a velocity of about 8.0 km s^‐1 were recorded. Large‐amplitude, later arrivals, beginning at distances near 100 and 150 km, have been interpreted to be part of the retrograde branches from the 8.0 and 7.33 km s^‐1 layers, respectively. Model studies indicate that a small positive velocity gradient is required between 17 and 30 km, and that the Moho is at a depth of 34 km. A third set of large amplitude, later arrivals starting at a distance near 250 km has been interpreted as most probably multiple refraction‐reflection arrivals from the 5.97 and 6.52 km s^‐1 layers. Correlation of this structure with the stratigraphic logs from exploratory oil wells in the Arafura Sea using layer velocities indicates that rocks younger than Jurassic appear to thin towards the east.     

Biogenic signature and ultra microfossils in ferromanganese nodules of the Central Indian Ocean Basin

Theories related to the precipitation mechanism of the metallic elements in marine manganese nodules have remained controversial between two schools of thoughts (1) chemical oxidation (abiotic origin) and (2) deposition of the metals through microbial enzymatic processes (biogenic origin). One of the most important evidence in support of the biogenic origin is the occurrence of fossilized microbes. However, well-documented literature in this regard is either lacking or very scanty in case of Indian Ocean nodules. Using high resolution FEG-SEM we have recorded various biogenic signatures and ultra microfossils in the ferromanganese nodule samples from Central Indian Ocean Basin (CIOB) that are presented in this paper. The microfossils are mostly protozoans belonging to varieties of bacteria, diatoms and foraminifera. Some of the features recorded in this study have perhaps never been reported before from any manganese nodules. The chemical compositions of these ultra microfossils indicate a high-level of manganese precipitation in and around them in comparison to the distant surrounding areas. While clumpy microbes are enriched with nickel, the rod shaped bacteria are rich in copper. Up to 4.70 wt.% nickel and 5.31 wt.% Cu have been recorded in the fossilized microbe bodies. The high abundance of biogenic features as well as microfossils in the ferromanganese nodules and their chemical compositions support arguments in favor of a dominant role of the microorganisms in the construction of the nodules of the CIOB.