豫南灵山岩体铀矿化特征

地处豫南的灵山岩体,分布着丰富的矿产资源。笔者以灵山岩体铀矿化分布特征为切入点,阐述灵山岩体铀矿化特征。该岩体铀矿化受构造、裂隙的控制,有利成矿部位在岩体中构造带与脉岩相交复合部位,矿化富集地段多含铁质、锰质和泥质,且热液蚀变发育。铀源来自岩体。具有4种矿化类型。总结其矿化特征,对豫南新县岩体、商城岩体的找矿具有一定指导意义。     

Deep sea navigation techniques

Accurate navigation forms an essential part of all research at sea and the deep ocean imposes it's own unique problems. This chapter discusses several of the techniques in current use on the research vessels of the Natural Environment Research Council (NERC), concentrating on those systems which provide global navigation facilities, as opposed to the more localised, coastal aids. Whilst most of the systems rely on surface propagation of radio waves, the use of acoustics and sea-bed mapping instruments constitute accurate alternatives for some sub-sea applications.     

Mercury speciation in surface and deep waters of the Mediterranean Sea

Mercury speciation and its distribution in surface and deep waters of the Mediterranean Sea were studied during two oceanographic cruises on board the Italian research vessel URANIA in summer 2003 and spring 2004 as part of the Med Oceaneor and MERCYMS projects. The study included deep water profiles of dissolved gaseous Hg (DGM), reactive Hg (RHg), total Hg (THg), monomethyl Hg (MeHg) and dimethyl Hg (DMeHg) in open ocean waters. Average concentrations of measured Hg species were characterized by seasonal and spatial variations. Overall average THg concentrations ranged between 0.41 and 2.65 pM (1.32 ± 0.48 pM) and were comparable to those obtained in previous studies of the Mediterranean Sea. A significant fraction of Hg was present as “reactive” Hg (average 0.33 ± 0.32 pM). Dissolved gaseous Hg (DGM), which consists mainly of Hg⁰, represents a considerable proportion of THg (average 20%, 0.23 ± 0.11 pM). The portion of DGM typically increased towards the bottom, especially in areas with strong tectonic activity (Alboran Sea, Strait of Sicily, Tyrrhenian Sea), indicating its geotectonic origin. No dimethyl Hg was found in surface waters down to the depth of 40 m. Below this depth, its average concentration was 2.67 ± 2.9 fM. Dissolved fractions of total Hg and MeHg were measured in filtered water samples and were 0.68 ± 0.43 pM and 0.29 ± 0.17 pM for THg and MeHg respectively. The fraction of Hg as MeHg was in average 43%, which is relatively high compared to other ocean environments. The concentrations reported in this study are among the lowest found in marine environments and the quality of analytical methods are of key importance. Speciation of Hg in sea water is of crucial importance as THg concentrations alone do not give adequate data for understanding Hg sources and cycling in marine environments. For example, photoinduced transformations are important for the presence of reactive and elemental mercury in the surface layers, biologically mediated reactions are important for the production/degradation of MeHg and DGM in the photic zones of the water column, and the data for DGM in deep sea indicate the natural sources of Hg in geotectonicaly active areas of the Mediterranean Sea.     

Artificial Upwelling of Deep Seawater Using the Perpetual Salt Fountain for Cultivation of Ocean Desert

Deep seawater in the ocean contains a great deal of nutrients. Stommel et al. have proposed the notion of a “perpetual salt fountain” (Stommel et al., 1956). They noted the possibility of a permanent upwelling of deep seawater with no additional external energy source. If we can cause deep seawater to upwell extensively, we can achieve an ocean farm. We have succeeded in measuring the upwelling velocity by an experiment in the Mariana Trench area using a special measurement system. A 0.3 m diameter, 280 m long soft pipe made of PVC sheet was used in the experiment. The measured data, a verification experiment, and numerical simulation results, gave an estimate of upwelling velocity of 212 m/day. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Zonal Pathway for NADW in the South Atlantic

Several large deployments of neutrally buoyant floats took place within the Antarctic Intermediate (AAIW), North Atlantic Deep Water (NADW), and the Antarctic Bottom Water (AABW) of the South Atlantic in the 1990s and a number of hydrographic sections were occupied as well. Here we use the spatially and temporally averaged velocities measured by these floats, combined with the hydrographic section data and various estimates of regional current transports from moored current meter arrays, to determine the circulation of the three major subthermocline water masses in a zonal strip across the South Atlantic between the latitudes of 19°S and 30°S. We concentrate on this region because the historical literature suggests that it is where the Deep Western Boundary Current containing NADW bifurcates. In support of this notion, we find that a net of about 5 Sv. of the 15–20 Sv that crosses 19°S does continue zonally eastward at least as far as the Mid-Atlantic Ridge. Once across the ridge it takes a circuit to the north along the ridge flanks before returning to the south in the eastern half of the Angola Basin. The data suggest that the NADW then continues on into the Indian Ocean. This scheme is discussed in the context of distributions of dissolved oxygen, silicate and salinity. In spite of the many float-years of data that were collected in the region a surprising result is that their impact on the computed solutions is quite modest. Although the focus is on the NADW we also discuss the circulation for the AAIW and AABW layers.     

大民屯凹陷地层水水文地质特征与油气聚集关系

对大民屯凹陷前第三系潜山、下第三系沙河街组地层水化学场研究发现，本区油田水总矿化度及二价阳离子浓度偏低，地层水总矿化度具有明显的垂向分带性，水体主要为陆相成因并受地表水渗入的影响较大，变质程度高，油田水的演化与盐类的溶解有关。该区地层水的流动受断裂和沉积砂体的控制，在水头压力、浮力动力场控制下其流动样式和分布规律反映了凹陷内油气的运聚规律，可为本区自生自储、新生古储式油气藏的判别提供有利证据。     

Bathymetry of Molloy Deep: Fram Strait between Svalbard and Greenland

The sea floor of Fram Strait, the over 2500 m deep passage between the Arctic Ocean and the Norwegian-Greenland Sea, is part of a complex transform zone between the Knipovich mid-oceanic ridge of the Norwegian-Greenland Sea and the Nansen-Gakkel Ridge of the Arctic Ocean. Because linear magnetic anomalies formed by sea-floor spreading have not been found, the precise location of the boundary between the Eurasian and the North American plate is unknown in this region. Systematic surveying of Fram Strait with SEABEAM and high resolution seismic profiling began in 1984 and continued in 1985 and 1987, providing detailed morphology of the Fram Strait sea floor and permitting better definition of its morphotectonics. The 1984 survey presented in this paper provided a complete set of bathymetric data from the southernmost section of the Svalbard Transform, including the Molloy Fracture Zone, connecting the Knipovich Ridge to the Molloy Ridge; and the Molloy Deep, a nodal basin formed at the intersection of the Molloy Transform Fault and the Molloy Ridge. This nodal basin has a revised maximum depth of 5607 m water depth at 79°8.5N and 2°47E.     

The impact of salt water inflows on the distribution of polycyclic aromatic hydrocarbons in the deep water of the Baltic Sea

Salt-water inflows into the Baltic Sea are important events for renewing the deep and bottom waters of the deep basins of the Baltic Sea. These events occur only at irregular intervals. The last strong event was in January 1993 followed by minor inflows in winter 1993/1994. As a result of these inflows, the deep water of the central Baltic basins was completely renewed.Based on extensive observations of polycyclic aromatic hydrocarbons (PAHs) in water, fluffy layer material and surface sediments between 1992 and 1998, the transformation of PAHs and the modification of their distribution in the Baltic deep water is discussed in connection with the spreading of the inflowing highly saline and oxygen-rich water along its pathway from the sills into the central basins. In the course of the inflows in 1993/1994, the PAH concentration in the deep water of the different basins increased significantly. The concentrations were elevated, at least by a factor of 2 and as much as seven to eight times (for the four-ring PAHs) compared to the previous and the following years. Two hypotheses for the causes were discussed: the inflowing salt water may have entrained more highly polluted surface water in the western Baltic Sea, or it may have entrained contaminated fluffy layer material or sediment particles along the route of transport.     

Beneath the surface: Characteristics of oceanic ecosystems under weak mixing conditions – A theoretical investigation

This study considers an important biome in aquatic environments, the subsurface ecosystem that evolves under low mixing conditions, from a theoretical point of view. Employing a conceptual model that involves phytoplankton, a limiting nutrient and sinking detritus, we use a set of key characteristics (thickness, depth, biomass amplitude/productivity) to qualitatively and quantitatively describe subsurface biomass maximum layers (SBMLs) of phytoplankton. These SBMLs are defined by the existence of two community compensation depths in the water column, which confine the layer of net community production; their depth coincides with the upper nutricline. Analysing the results of a large ensemble of simulations with a one-dimensional numerical model, we explore the parameter dependencies to obtain fundamental steady-state relationships that connect primary production, mortality and grazing, remineralization, vertical diffusion and detrital sinking. As a main result, we find that we can distinguish between factors that determine the vertically integrated primary production and others that affect only depth and shape (thickness and biomass amplitude) of this subsurface production layer. A simple relationship is derived analytically, which can be used to estimate the steady-state primary productivity in the subsurface oligotrophic ocean. The fundamental nature of the results provides further insight into the dynamics of these “hidden” ecosystems and their role in marine nutrient cycling.     

Ghost fishing in European waters: Impacts and management responses

In this paper we review levels of net loss, what happens to the gear once it has been lost, and the resulting levels of ‘ghost catches’ made in passive net fisheries in the EU. We also consider ghost catches resulting from lost gear in other types of fisheries, and the extent to which the value of ghost catches has been quantified. We consider why fishing gear is lost, and profile common management responses. We present a cost benefit model to assess the relative cost effectiveness of different management measures, and suggest that gear retrieval programmes may provide less value for money than other management responses.