从海洋内部研究海洋

几百年来,人类总是从海洋外面——在船上或者岸上研究海洋。随着技术的最新发展,人类现在可以从海洋内部来研究海洋。简要讨论了海底观测系统和活动观测平台为各领域的海洋研究提供的空前机遇,并指出中国发展海洋科学必须对这一新趋势给予密切注意。     

加拿大海王星:科学、运行、管理

加拿大海王星是世界最大的海底缆接科学观测网,于2009年开始运行.它连接了位于不同水深和不同海洋地质环境的大批观测仪器,把数据连续不断地通过互联网传给科学家和大众.海王星的建立是为了推动地震过程和大地构造、海底地下流体、海洋生物与气候变化、深海生态系统、工程和信息科学等五大科学命题的研究.为最大程度地推动国际合作,加速科学发展步伐,它的系统使用完全开放,数据全部免费公开,这在科学史上前所未见.这种全方位、全开放的复杂庞大的科研系统需要高超的管理方法和优良的学术环境.     

海底热液活动区地微生物学研究中的分子生物学技术

海底热液活动区微生物生态及其相关研究一直是近年来海洋地微生物学研究的热点之一。有关发现不断挑战着人们对微生物的代谢机理、生存极限、元素地球化学循环作用等方面的传统认识。与传统的富集培养方法相比,主要基于16S rRNA基因和特征性功能基因系统的发育分析等技术为研究这一极端环境中栖息的微生物群落提供了更为系统和全面的手段。这些技术包括基因文库构建(16S rRNA和其它功能基因)、变性梯度凝胶电泳(DGGE)、末端限制性片段长度多态性分析(T-RFLP)、荧光原位杂交(FISH)以及定量PCR等。目前,上述技术手段广泛应用于全球海底热液活动区地微生物学的研究,在丰富地球物种多样性、调查微生物参与的元素地球化学循环过程、研究微生物与矿物的相互作用以及生命起源与演化等方面取得了大量的研究成果。简要介绍了常规分子生物学技术的基本原理及其在海底热液活动区地微生物学研究中的应用现状。     

深渊着陆器坐底位置的精确测量和反演计算

深渊着陆器在下潜过程中,由于受到海流的影响,其坐底位置会偏离投放点,偏离量和偏离方向很难估计,而声学水下定位方法在深渊海区不太适用.通过在海面进行气枪十字放炮作业,利用炮点准确位置和时间信息,以及海底地震仪(Ocean Bottom Seismometer,OBS)记录的直达水波到时,对深渊着陆器的坐底位置进行精确测量可以提供有效定位数据.该方法对采集得到的数据进行预处理,使用蒙托卡洛方法结合最小二乘法,对万泉号着陆器实际坐底位置进行了反演校正,得到三个潜次的位置校正偏移量分别为211m、178m、861m,偏移方向各不相同,校正精度为±20m,比以往的定位精度大为提高.此外,该方法测量确定了三个海底标志物的精确位置,为未来万米无人或载人潜器提供了可靠的水下参考坐标.     

滨州海岸带土壤和海底沉积物重金属空间分布特征

通过对滨州近海海域海底沉积物测试数据及海岸带陆域土壤地球化学分析,对滨州海岸带陆域土壤和海底沉积物中7种重金属(Hg,Cd,Pb,Cu,Zn,Cr,Ni)的空间分布特征进行了研究,并绘制了各指标含量陆海联合分区图。分析结果表明,滨州市海岸带重金属元素含量基本上均低于国标规定的海洋一类沉积物的最高标准,仅有个别元素含量超过一级标准值,表明局部存在一定的重金属污染。从滨州海岸带重金属含量空间分布上来看,除Hg元素外,其余重金属元素含量呈现一定的规律,基本上陆域含量高于海域含量,且大部分元素都呈现出陆域城镇值高,郊区值低的态势。区内化工企业较发达,Ni,Cr属于中度变异区,Cd,Hg,Pb属于高度变异,受人为影响因素较大,考虑区内土壤及海底沉积物重金属富集主要来源于工业"三废"。     

西太平洋典型弧后盆地的地质构造、岩浆作用与热液活动

研究了西太平洋典型弧后盆地冲绳海槽和马努斯海盆的区域地质背景、岩浆岩、喷口流体、热液柱、沉积物以及多金属硫化物。结果表明,冲绳海槽在构造和地球物理特征上南北分异,从北向南地壳厚度减薄,南部重力异常变化大,发育条带状磁异常,中部则具有最高的热流值。马努斯海盆的重力异常变化较小,磁力异常呈东西向展布,海底扩张中心附近出现磁异常条带。马努斯海盆已出现洋壳,冲绳海槽的地壳属于过渡性地壳,在中南部的地堑中可能已出现洋壳。 冲绳海槽与马努斯海盆玄武岩的岩浆是由地幔源区部分熔融产生的原始岩浆与板块俯冲组分混合构成。中酸性岩与基性岩具有相同的岩浆物质来源,是玄武质岩浆结晶分异的产物。与马努斯海盆火山岩相比,冲绳海槽火山岩存在不同程度的地壳混染。 冲绳海槽的喷口流体为富含金属元素（Mn、Fe、Zn、Pb）的酸性高温（高达320 °C）流体,其热液柱中的Zn2 、Cd2 、Pb2 、Cu2 离子浓度明显高于正常海水。马努斯海盆的热液柱呈现出CH4、Mn、Al、δ3He正异常及pH负异常的特征。与马努斯海盆PACMANUS热液区的喷口流体（220–276 °C、pH = 2.5–3.5）相比,DESMOS热液区的喷口流体温度（≥88–120 °C）相对较低,酸性更强（pH ≤ 2.1）,二者较低的δ34SH2S和δD值表明岩浆演化过程中有酸性挥发分进入岩浆流体。冲绳海槽与马努斯海盆含金属沉积物的分布及其元素含量特征具有差异,相应地,两个弧后盆地含金属沉积物中的微生物群落也不同。冲绳海槽和马努斯海盆热液区均具富Zn型、Ba-Pb-Zn型、Si-硫化物型和Si-硫化物-硫酸盐型热液产物。与冲绳海槽的多金属硫化物相比,马努斯海盆中多金属硫化物的Pb和Au含量较低。     

Geometric corrections on sidescan sonar images based on bathymetry. Application with SeaMARC II and Sea Beam data

Acoustic backscatter images of the seafloor obtained with sidescan sonar systems are displayed most often using a flat bottom assumption. Whenever this assumption is not valid, pixels are mapped incorrectly in the image frame, yielding distorted representations of the seafloor. Here, such distortions are corrected by using an appropriate representation of the relief, as measured by the sonar that collected the acoustic backscatter information. In addition, all spatial filtering operations required in the pixel relocation process take the sonar geometry into account. Examples of the process are provided by data collected in the Northeastern Pacific over Fieberling Guyot with the SeaMARC II bathymetric sidescan sonar system and the Sea Beam multibeam echo-sounder. The nearly complete (90%) Sea Beam bathymetry coverage of the Guyot serves as a reference to quantify the distortions found in the backscatter images and to evaluate the accuracy of the corrections performed with SeaMARC II bathymetry. As a byproduct, the processed SeaMARC II bathymetry and the Sea Beam bathymetry adapted to the SeaMARC II sonar geometry exhibit a 35m mean-square difference over the entire area surveyed.On leave at the Naval Research Laboratory, Code 7420, Washington D.C. 20375-5350.     

Variations in axial processes on the Mid-Atlantic Ridge: The median valley of the MARK area

Submersible observations and photogeology document dramatic variations in the distribution of young volcanic rocks, faulting, fissuring, and hydrothermal activity along an 80 km-long segment of the Mid-Atlantic Ridge south of the Kane Transform (MARK Area). These variations define two spreading cells separated by a cell boundary zone or a small-offset transform zone. The northern spreading cell is characterized by a median ‘neovolcanic’ ridge which runs down the axis of the median valley floor for 40 km. This edifice is as much as 4 km wide and 600 m high and is composed of very lightly sedimented basalts inferred to be < 5000 years old. It is the largest single volcanic constructional feature discovered to date on the Mid-Atlantic Ridge. The active Snake Pit hydrothermal vent field is on the crest of this ridge and implies the presence of a magma chamber in the northern spreading cell. In contrast, the southern cell is characterized by small, individual volcanos similar in size to the central volcanos in the FAMOUS area. Two of the volcanos that were sampled appear to be composed of dominantly glassy basaltic rocks with very light sediment cover; whereas, other volcanos in this region appear to be older features. The boundary zone between the two spreading cells is intensely faulted and lacks young volcanic rocks. This area may also contain a small-offset ( < 8 km) transform zone. Magmatism in the northern cell has been episodic and tens of thousands of years have lapsed since the last major magmatic event there. In the southern cell, a more continuous style of volcanic accretion appears to be operative. The style of spreading in the southern cell may be much more typical for the Mid-Atlantic Ridge than that of the northern cell because the latter is adjacent to the 150 km-offset Kane Transform that may act as a thermal sink along the MAR. Such large transforms are not common on the MAR, therefore, lithosphere produced in a spreading cell influenced by a large transform may also be somewhat atypical.     

地理信息系统的发展及其在海洋领域中的应用

系统介绍了海洋地理信息系统(MGIS)的特点、成果和发展趋势,它使海洋信息数据的建库和管理向科学化、可视化、便捷化方向发展。海底蕴藏着丰富的矿产资源,而海岸带聚集着地球上大部分的人口和城市。因此,“数字海底”和“海岸带”研究是当前MGIS研究的切入点。