三种体系萃取分离-液闪测定海水中234Th的比较研究

本文对TOA萃取剂萃取钍适宜的操作条件及萃取溶剂进行了试验,提出了TOA/苯萃取234Th的最佳条件: 在 1cm3含 234Th的 6mol/dm3 HNO3 溶液中,用体积比为 0. 5的TOA/苯溶液 2cm3 萃取,然后用 2cm3 1. 0mol/dm3 H2SO4反萃取,最高萃取率达 94%.对TOA/苯、TBP/煤油和TTA/苯这 3种萃取体系的萃取效率及其影响因素、萃取机理、成本等做了比较,认为 3种体系各有利弊,但均可有效地应用于相关的海洋学研究中.     

超低水平液闪谱仪测定雨水、海水中的宇生核素32P和33P

本研究旨在建立用超低水平液闪谱仪测定雨水、海水中的宇生核素32P3、3P的方法.通过对液闪谱仪的主要性能与技术参数进行优化设置,对液闪谱仪的效率及能量进行刻度,建立淬灭校正曲线,探讨影响测量本底的因素,实现液闪谱仪对样品的优化测量.并通过液闪谱仪对厦门沿岸地区雨水及厦门湾海水进行测量,得到2004年3月至2005年2月雨水中32P3、3P的月平均比活度分别为0.30×10-2~3.18×10-2、0.28×10-2~3.05×10-2Bq/dm3,33P/32P)A.R.月平均值介于0.74~0.96之间,平均为0.87±0.03;厦门湾海水中32P、33P的比活度分别为1.52×10-2~4.62×10-2、1.28×10-2~3.72×10-2Bq/m3,33P/32P)A.R.为0.81~0.91.     

海水中228Th、234Th、228Ra的联合富集与测定

采用大体积现场泵方法同时采集不同粒级的^228Th、^234Th及溶解态的^228Th、^234Th、^228Ra．以小体积MnO2共沉淀-β计数法测定海水中的总^234Th活度（A＇TTh）；用Goflo采水器采集6～10dm^3海水，继而过滤收集颗粒物质并测定其^234Th的活度（A’PTh）；以α能谱测定分离纯化后的^228Th；对^228Ra则是采用测定其子体^228Ac的β放射性方法．采用此流程分析了南海2004年2月航次A1站住的样品，获得了较好的结果．     

海水U、Th长寿命核素的高精密度MC-ICP-MS测定方法

建立了适合海水U、Th同位素高精密度测量要求的MC-ICP-MS方法.确定了采用Mg(OH)2共沉淀法富集海水U、Th同位素时的最佳NH3·H2O浓度为0.14 mol/dm3.采用CRM-145 U标准溶液,经质量分馏、电子倍增器增益、丰度灵敏度、仪器及试剂本底和记忆效应等校正后,历时3个月得235U/238U和234U/238U的准确度分别优于0.05%和0.08%,精密度分别优于0.12%和0.10%.将该方法应用于台湾海峡B9站位3份平行水样中U、Th同位素含量及比值的测定,得238U平均含量为3.05±0.05μg/kg,234U/238U平均值为(6.28±0.11)×10-5,U含量及其同位素比值的标准偏差均小于3%;232Th的平均含量为(1.66±0.04)×103pg/kg,232Th/230Th平均值为(1.95±0.01)×105,Th含量及其同位素比值的标准偏差均小于2%.测定结果与海区的水文学条件及物质来源相吻合,证明了方法的可靠性.     

海水中-氧化氮的化学发光法测定

基于鲁米诺-H2O2混合溶液作为发光液与海水中NO发生反应产生发光信号的原理,提出了一种测定海水中痕量NO的化学发光法.确定了化学发光法测定NO的最佳条件:pH9.2、浓度1×10-2 mol/dm3的碳酸盐为缓冲体系,鲁米诺浓度为8.4×10-5 mol/dm3,H2O2浓度为1×10-2 mol/dm3,测定温度为...     

泥蚶肌肉组织蛋白质双向电泳体系的建立

本研究建立了泥蚶肌肉组织蛋白质的双向电泳体系.提取泥蚶肌肉组织全蛋白,进行了双向电泳分离的初步尝试,并对各个关键因素和环节进行了优化比较.优化的裂解液配方是8mol/dm3 Urea,1.5mol/dm3 Thioruea,4% CHAPS,10mmol/dm3 Tris,2mmol/dm3 TBP,0.2%Bio-Lyte3/10ampholyte,1mmol/dm3 PMSF以及1mmol/dm3 EDTA.使用pH值为4～7的IPG胶条进行被动水化上样,等电聚焦采用缓慢升压模式,电泳参数设置和染色方法等根据Bio-rad公司推荐的进行调整.最终获得了较满意的双向电泳图谱,具有较高的分辨率和重复性,成功建立了泥蚶肌肉组织蛋白质双向电泳分离体系.     

海水中锶-90和铯-137的同时测定

本文研究了海水中痕量锶—90和铯—137同时测定的方法,在酸性条件下采用磷钼酸铵(AMP)浓集铯—137;0.45mol/dm3 HDEHP—正庚烷直接萃取钇—90(锶—90子体),沉淀源分别为碘铋酸铯、草酸钇进行低本底β—计数。本方法简便、快速,对主要核素去污效果较好;精密度和准确度均好,测定方法最低检测活度90Sr为4.5×103Bq/dm3,137Cs为5.7×10-3Bq dm3。     

海洋放射年代学的若干问题

海洋放射年代学是同位素地质学的一门分支学科.它主要是应用天然放射性核素:230Th、231Pa、234U、238U、232Th、226Ra、210Pb、14C测定珊瑚礁、鲕岩、海泥、软体动物贝壳的年龄,测定锰结核和海洋沉积物积累的速度;研究放射性元素在海水、悬浮物和沉积物中垂直和空间分布的特征;讨论放射性元素和同位素存在形式和沉淀机理;阐述海洋物质来源;探讨锰结核成因等.     

海水中丙烯酸的高效液相色谱法建立及应用

建立了一种测定海水介质中丙烯酸的高效液相色谱法。采用耐纯水相和较低pH的Agilent SB-Aq-C18柱(100 mm×4.6 mm i.d.,5 μm), 0.35%磷酸溶液(pH=2)为流动相,使用紫外检测器,检测波长为210 nm,外标法定量测定。丙烯酸的保留时间在14.2~ 14.9 min,方法的检出限为4 nmol/dm3(S/N=3),在0.01~10 μmol/dm3的范围内均有良好的线性关系,相关系数可达0.999 6,加标回收率为95.4%~98.1%,相对标准偏差为1.3%~1.6%(1.04~2.32 μmol/dm3)。采用0.2 μm滤膜重力过滤冷藏的办法来保存海水丙烯酸样品。检测出2011年5月份青岛近海海水中丙烯酸的平均浓度为(0.101±0.069) μmol/dm3;海洋微藻球形棕囊藻在整个生长周期内培养体系中丙烯酸的浓度为0.339~2.219 μmol/dm3。     

MnO2共沉淀直接β计数测定小体积海水中的234Th

探讨了MnO₂共沉淀直接β计数测定小体积海水中234Th方法在固体闪烁α/β计数仪上实现的可能性,对实验流程空白、流程化学回收率、仪器探测效率、MnO₂共沉淀量对全程回收率的影响以及检测核素的特征性等进行了研究.结果表明,该方法具有稳定的流程空白和全程回收率、高的探测效率和化学回收率,且所检测核素与234Th的理论半衰期基本吻合.将该流程应用于亚热带北太平洋表层水中234Th的分析也得到了令人满意的结果.与传统方法相比,该方法具有流程简单、所用水样体积小、快速获得结果等特点,适合于船载分析,由此可实现高时空分辨率数据的获取,为海洋颗粒有机碳输出通量以及颗粒物迁移速率的研究提供了更好的分析手段.     

Assessing the Validity of Seismo-Acoustic Predictor Equations for Obtaining Seabed and Sub-Surface Sediment Physical Properties

The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Interannual Sea Level Variations and Annual Tides in the Northwestern Pacific

Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone.     

Flow Cytometric Analysis of Coastal Lagoon Bacterioplankton and Picophytoplankton: Fixation and Storage Effects

The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics.     

INFORMATION FOR AUTHORS

<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology,     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Net Sand Transport Direction in a Tidal Inlet, using Foraminiferal Tests as Natural Tracers

The relationship between the flux of exotic benthic foraminiferal tests (i.e. tests which are supplied from open-sea sources alone) in a tidal inlet and that of bulk sediment was analysed, which can be expressed as two first-order linear equations. According to this relationship, in order to determine net sediment transport directions in the entrance, the test concentration in surficial sediments of the tidal basin can be compared against a ‘ critical level ’. The critical level is determined for the conditions that no net transport of bulk sediment is present within the entrance. If the observed concentration (averaged over the tidal basin) is higher than the simulated critical level, then the net sediment transport is directed to landward. This method is applied to the analysis of net sand transport at Christchurch Harbour, a tidal inlet system located in southern England. In this investigation, concentrations of exotic foraminiferal tests in the surficial sediments of the tidal basin and ebb tidal delta area were obtained from the analysis of sea-bed sediment samples. A series of probable critical levels were calculated based upon the data sets with regard to: (1) sediment discharge from the rivers; (2) magnitude of sediment discharge within the entrance during the ebb; (3) the test concentration outside the harbour; (4) the thickness of the moving layer; and (5) two parameters associated with dispersive processes. The results show that the concentration in the tidal basin sediment is higher than a number of simulated critical concentrations for representative cases. Consequently, the high level of the concentration of exotic benthic foraminiferal tests within the harbour should be explained as a result of landward net transport of sands within the entrance.