Measuring and modelling temporal trends of 226Ra in waters of a Spanish estuary affected by the phosphate industry     

Periáñez R 《Marine environmental research》2005,60(1):35-49

The presence and temporal evolution (1990-2001) of (226)Ra in a tidal estuary affected by the phosphate industry has been investigated. Water samples collected in the course of four separate sampling campaigns were analysed for (226)Ra content using a gas flow proportional counter following Ba coprecipitation. Two (226)Ra sources have been identified: direct discharges from the industrial complex and run-off from a phosphogypsum pile. Although activity levels are similar, or even higher, than those found in other environments affected by the phosphate industry, there has been a general decrease in contamination since direct discharges ceased in 1998 due to new regulations from the EU. However, sediments are now acting as a source of Ra to the water column due to redissolution processes. A numerical model of the estuary has been developed to describe quantitatively the experimental results. The model solves the hydrodynamics and the dispersion equation of (226)Ra including interactions with sediments. Model results are, in general, in good agreement with observations.  相似文献   

Anthropogenic trace metals in sediment and settling particulate matter on a high-energy continental shelf (Sydney,Australia)     

Matthai C  Birch GF  Bickford GP 《Marine environmental research》2002,54(2):99-127

The anthropogenic contribution of trace metals to settling particulate matter (SPM) and surficial sediments was determined on the high-energy continental shelf adjacent to Sydney, Australia. Settling particulate matter and surficial sediment was collected in the vicinity of a major sewage outfall and at five control sites on the middle shelf (80-100 m water depth). Sediment traps were deployed on 10 occasions for up to 2 weeks during the summer and winter of 1995 and SPM was analyzed for Ag, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn. Cobalt, Fe, Mn and Ni act conservatively in SPM and in sediments regionally and are used as normalizing elements to determine anthropogenic enrichment. Surficial sediments and SPM are enriched in Ag, Cr, Cu, Pb and Zn near a major ocean outfall and at four of the five control sites, although sewage particles contribute < 5% of trace metals in the total sample. Silver is the most sensitive trace metal tracer for establishing the presence of sewage particulate matter. Sewage particulate matter flux near the outfall was estimated using a two end-member mixing model and is below 0.5 g m(-2) day(-1) during all deployment periods. The mean sewage particulate matter flux at sampling locations 30 km and 60 km north of the outfall are <0.13 g m(-2) day(-1) and <0.01 g m(-2) day(-1), respectively, indicating an efficient dispersal of anthropogenic material on this high energy continental shelf.  相似文献   

Patterns of heritability of decreased EROD activity and resistance to PCB 126-induced teratogenesis in laboratory-reared offspring of killifish (Fundulus heteroclitus) from a creosote-contaminated site in the Elizabeth River,VA, USA     

Meyer J  Di Giulio R 《Marine environmental research》2002,54(3-5):621-626

Killifish (Fundulus heteroclitus) from a highly contaminated site on the Elizabeth River are resistant to the acute toxicity and the cytochrome P4501A (CYP1A)-inducing activity of both the sediments from the site and chemically pure polycyclic aromatic hydrocarbons (PAHs). These effects are highly heritable for one generation, but heritable to a lesser degree by subsequent generations, in clean conditions in the laboratory. We show that offspring of this population of Elizabeth River killifish are also resistant to the teratogenicity and P4501A-inducing activity of PCB congener 126, a prototypical coplanar halogenated aromatic hydrocarbon (HAH). Furthermore, the pattern of greater resistance to acute toxicity and P4501A-inducing activity in the first generation and less in subsequent generations is also observed upon exposure to PCB-126.  相似文献   

1985年空间海洋学的状况和展望     

D.J.贝克  倪振荣 《海洋开发与管理》1986,(3)

1984年海洋学工程的主要措施是在空间建立海洋观察站。新的海军遥控海洋测向系统卫星(NROSS)和欧洲空间站的地球资源卫星(ERS—Ⅰ)已得到政府的批准,列入了预算项目,开展了利用卫星调查内容的计划和操作运行的计划。NROSS 的传感器有用于风的 NASA(国家航空和航天局)的传播计量器;用于水面温度,冰的性质和海冰边端的微波无线  相似文献   

大西洋中脊的热液矿泉     

R．P.VonHerzen 《海洋地质前沿》1997,(2)

在过去10年中，通过国际合作，对大西洋中肯的热液矿泉及周围地质背景进行了研究。TAG热液矿泉位于26°N，45°W，距大西洋中脊轴数公里，它是世界卜已发现的最大热液矿泉之一．这个活动的热泉位于一直径为10m的烟囱上，该烟囱位于一直径为150－200m、高40m的椭圆形硫化矿山上．在这个硫化矿山附近几公里范围内还发现了几个不活动的热泉。TAG靠近两条转换断层之间的大西洋中脊．区域重力调查表明，TAG北部的剪切带在向北漂移．分析TAG海底玄武岩表明，源岩在10－15km深处．从旁侧声纳资料看出，TAG由两个复杂的烟囱组成．近海底地球…  相似文献   

LARGE-SCALE CIRCULATION CONDITIONS AFFECTING THE HURRICANE FORMATION OVER THE NORTH ATLANTIC OCEAN     

丁一汇  ELMAR R. REITER 《海洋学报(英文版)》1985,4(1):21-34

A contrasting study of the large-scale circulation features responsible for months or seasons with many hurricanes and those with few hurricanes has revealed that the frequency of hurricane formation over the North Atlantic Ocean is enhanced by the following conditions:There exists a well-developed subtropical high-pressure belt displaced to the north; a deep Icelandic low; a stronger-than-normal polar vortex with a deep polar trough dipping far southward along the eastern part of the United States; a dominant high-pressure ridge over western Canada and the United States; and a jet stream displaced northward over these regions. At 200 hPa, an anomalous anticyclonic circulation prevails over the subtropical North Atlantic. A stronger-than-normal upper easterly flow prevails. Positive sea surface temperature anomalies prevailing on a seasonal or long-term basis tend to be favorable for the formation of hurricanes.  相似文献   

CHARACTERISTICS ON INTERANNUAL VARIATIONS OF NORTH PACIFIC SST AND ITS RELATION TO EAST ASIA CLIMATE     

解思梅  TAKASHI AOKI  MASATOSHI M. YOSHINO 《海洋学报(英文版)》1987,6(1):68-79

The interannual variations of the monthly sea surface temperature (SST) in the North Pacific (including Equatorial East Pacific) during 1951-1980 are analysed by means of EOF method. The findings are:(1) In the cold and warm ocean current areas, such as the North Pacific Current, the California Current and the Equatorial East Pacific areas, the convergence speeds are the fastest, while in the Kuroshio and the western part of the North Equatorial Current areas they are fast only in winter.(2) The physical features of the first 3 eigenvectors are obvious. The first eigenvector shows that the SST values are high in the south and low in the north in the latitudinal distribution of the SST field. The warm current area, i.e. the northwestern part of the North Pacific is positive and the cold current area, i.e. the southeastern part of the North Pacific including the Eastern Equatorial Pacific is negative. The zero line of the 2nd eigenvector field runs from northeast to southwest, in the same direction as the  相似文献   

Molecular identification of bloom-forming species Phaeocystis globosa (Pryninesiophyta) and its dispersal based on rDNA ITS sequence analysis     

Chen Yueqin  Shao Peng  Wang Ning  Zhou Hui  Qu Lianghu  Linda K. Medlin 《海洋学报(英文版)》2003,22(2):243-253

The colony-forming Phaeocystis species are causative agents of dense bloom occurrences in coastal waters worldwide. It is difficult to separate them because of the different morphologies associated with their colonial stages. In this study we applied molecular approaches to analyze the genetic variation of Phaeocystis globosa and Phaeocystis pouchetii from several geographic regions, and to assist in tracing the dispersal of bloom-forming Phaeocystis species in coastal waters of China. The sequences of the internal transcribed spacers (ITS1 and ITS2) of rDNA and the 5.8S ribosomal RNA gene of Phaeocystis strains were determined. Sequence comparison shows that P.globosa was the most divergent to P. pouchetii, exhibiting sequence divergence higher than 0.08. However, lower genetic divergences existed between strains of P.globosa. The sequence comparison of the Phaeocystis rDNA ITS clearly shows that the species isolated from the southeast coast of China is identified as P.globosa rather than P. cf. pouchetii or other species. Furthermore, the significance of rDNA variation in distinct global populations of P.globosa suggested it might have had sufficient time to accumulate detectable mutations at the rDNA locus, supporting the hypothesis of ancient dispersal of P.globosa to many areas, meaning that P.globosa blooms in the coastal waters of China are endemic rather than a newly introduced species or a foreign source. Finally, based on the high divergent region of rDNA ITS, a pair of species-specific primers for P.globosa were designed, they could be useful to detect the presence of this species in mixed plankton assemblages or flagellate stages that are recognized with diffculties by means of conventional microscopy.  相似文献   

似海底反射的地震速度和AVO效应     

JoseM.Carcione UmbertaTinivella 《海洋地质》2002,(2):23-40,75

我们将浓度和压力作为一个函数得到冰和含气体水合物的地震波速度。同以往以简单的慢度和平均模量及双相模型为基础的理论不同，我们使用了Biot类型的三相理论，这一理论考虑了二种固体（颗粒和冰或笼形物）和一种液体（水）的存在，以及一个含气和水的多孔隙基质。对于固体的Berea砂岩，低于0℃时的纵波理论估计值过低，在含有冰－颗粒相互作用和颗粒胶结时与实验数据产生了好的吻合。严格地讲，水的比例与温度紧密相关。假定已知孔隙的平均半径和标准偏差，那么在一给定温度下的波速拟合就能对整个温度范围的速度进行预测。通过一个粘弹性的单相结构模型来计算反射系数。本文的分析是针对游离气带的顶部（位于含气体水合物的沉积层下）和底部（上履于饱含水的沉积层）进行的。如果似海底反射仅仅是由于胶结气体水合物与含游离气沉积层的分界面造成，我们可以得出结论：（1）在一定的气体饱和度下，很难估算低浓度情况下气体水合物数量。然而，水合物的高、低浓度还是可以区分的，因为它们分别呈现正和负的异常；（2）游离气和饱和度可以从反射振幅中而不是从异常类型中获取；（3）P波转化为S波的反射系数是指示高含量的气体水合物和游离气一个较好指示。另一方面，对于未胶结的沉积物，振幅随偏移距变化曲线总是为正。  相似文献   

“大洋矿产国际会议——天然气水合物专题”论文摘要——4、7100年前最大洪泛期对黑海天然气水合物储集体影响的模拟     

J.Poort  杨木壮 《海洋地质》2002,(3):30-31

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