砂岩中骨架颗粒溶解的理论

我们发现,长石和岩屑骨架颗粒的溶解作用(FGD)对于可溶颗粒大于10%的砂岩的储集性来说具有重要意义。据集些储集砂岩的研究,其骨架颗粒溶解孔隙度可高达70%左右,其平均孔隙度约为可见孔隙的30%。骨架颗粒溶解作用不能明显地增加储层的渗透率。但是,我们发现,骨架颗粒溶解孔隙度的发育数量是砂岩原始渗透率的函数。我们认为,页岩中的粘土及有机成熟作用为骨架颗粒溶解产生了必要的水、酸及络合剂。骨架颗粒溶解的溶剂被排驱至砂岩中,在那里长石和岩屑被溶解了,而且由此产生的溶解铝被络合,并搬运至砂岩之外。     

Where do periodic variations in the discharge of a well become negligible?

A rule of thumb is presented to determine where variations in the discharge of a pumping well have a significant influence on the flow in an aquifer. The rule of thumb relates the period of the variation of the discharge to the distance from the well beyond which the transient effect on the flow in the aquifer is insignificant. For example, when an irrigation well pumps intermittently during the growing season, the rule may be applied to determine the distance from the well beyond which flow in the aquifer can be simulated with an average discharge during the growing season; the distance from the well beyond which flow can be simulated with a steady, yearly averaged discharge can also be computed.     

A quantitative analysis on the Egyptian Mediterranean waters

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The macroinfauna of the Galician sandy beaches (NW Spain) affected by the Prestige oil-spill

Eighteen sandy beaches were sampled along the 1659 km of the Galician coast (NW Spain) six months after the Prestige oil-spill to study the impact of the fuel and the clean-up activities on the macroinfauna community. A transect was extended at each beach, from above the drift line to below the swash line at five sampled levels; at each level six 0.05 m2 replicates were taken to a depth of 30 cm and sieved through a 1mm mesh, and the organisms collected and preserved. Results were compared with previous data obtained using the same procedures. The macroinfauna was numerically dominated by the amphipod Pontocrates arenarius, the isopod genus Eurydice, the polychaete Scolelepis squamata, and the amphipod Talitrus saltator. As a result of the Prestige oil-spill and the clean-up activities, beach populations were reduced, with Eurydice and S. squamata as the most affected taxa.     

http://www.sciencedirect.com/science/article/pii/S1674987111000508

This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization.We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit(Yangchun,Guangdong Province, China) and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland(Australia).Two modelling approaches,discrete deformation modelling and continuum coupled deformation and fluid flow modelling,are involved.The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit,and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures.The continuum coupled deformation and fluid flow model indicates that pattern of the Cuveins near the Shilu deposit is the result of shear strain localization,development of dilation and fluid focussing into the dilatant fracture segments.The 3D case-study models(with deformation and fluid flow coupling) on the Hodgkinson Province generated a number of potential gold mineralization targets.     

PCBs in Central Vietnam coastal lagoons: levels and trends in dynamic environments

PCBs were analysed in surficial sediments and selected sediment cores collected between 2002 and 2008 in Central Vietnam coastal lagoons. The aim was to determine contamination levels and trends, and to evaluate the effects of anthropogenic pressures and natural events. Samples were mostly fine-grained with low total PCB concentrations (0.367-44.7 μg kg⁻¹). Atmospheric transport and post depositional processes modify to some degree the fingerprint of PCB inputs to the environment favouring the predominance of 3, 4 and 5 chlorinated congeners. The similarity of congener distributions in contemporary surficial samples also suggests the presence of a unique source over the entire study area, probably connected to mobilisation and long range transports from land-based stocks. The removal of consistent sediment layers is hypothesised based on repeated samplings of the same area. Natural meteorological events (such as typhoons) are suspected to be responsible for these sediment losses.     

英国气象局长期天气预报业务的技术方法和商业价值

英国气象局的长期天气预报,是每月第二周的星期一发布。预报时段为1—5天,6—15天和16—30天。预报区有10个,预报要素是平均气温和降水。制作这些预报,首先是报出这三个预报时段的平均地面气压(1—5天的预报只报1000—500hPa 的厚度场)。所使用的预报方法如表1:     

Efficacy of a multi-metric fish index as an analysis tool for the transitional fish component of the Water Framework Directive

The WFD has introduced an international commitment to assess the ecological status of transitional waters (TWs), within which fish communities are a key biological monitoring component. The Transitional Fish Classification Index (TFCI) outlined in this paper uses 10 ecological measures to analyse fish populations caught from various ecological niches using a variety of gear types within the Thames estuary. These reach and method-specific communities are then compared to a reference population created from a 'healthy' population from TWs of a similar type. The results indicate a progressive downstream increase the quality of fish communities, consistent with previous work; variation between methods can be accounted for by gear selectivity. Overall, the TFCI is an effective communication tool for converting ecological information into an easily understood format for managers, policy makers and the general public.     

Authigenic Gypsum in Gas-Hydrate Associated Sediments from the East Coast of India (Bay of Bengal)

Authigenic gypsum crystals, along with pyrite and carbonate mineralization, predominantly calcites were noticed in distinct intervals in a 32 m long piston core, collected in the gas hydrate- bearing sediments in the northern portion of the Krishna-Godavari basin, eastern continental margin of India at a water depth of 1691 m. X-ray diffraction and energy dispersive spectrum studies confirm presence of pyrite, gypsum, calcite, and other mineral aggregates. The occurrence of gypsum in such deep sea environment is intriguing, because gypsum is a classical evaporite mineral and is under saturated with respect to sea water. Sedimentological, geochemical evidences point to diagenetic formation of the gypsum due to oxidation of sulphide minerals (i.e. pyrite). Euhedral, transparent gypsum crystals, with pyrite inclusions are cemented with authigenic carbonates, possibly indicating that they were formed authigenically in situ in the gas hydrate-influenced environment due to late burial diagenesis involving sulphate reduction and anaerobic oxidation of methane (AOM). Therefore, the authigenic gypsums found in sediments of the Krishna-Godavari and Mahanadi offshore regions could be seen as one of the parameters to imply the presence of high methane flux possibly from gas hydrate at depth.     

Remotely sensed assessment of water quality levels in the Pearl River Estuary, China

In this paper, a method of assessing water quality from satellite data is introduced. The composite pollution index (CPI) was calculated from measured chemical oxygen demand (COD) and nutrient concentration. The relationships between CPI and 240 band combinations of SeaWiFS water-leaving radiance were analyzed and the optimal band combination for estimating CPI was chosen from the 240 band combinations. An algorithm for retrieval of CPI was developed using the optimal band combination, (L₄₄₃ × L₅₁₀)/(L₄₁₂ + L₄₉₀). The CPI was estimated from atmospherically corrected SeaWiFS data by employing the algorithm. Furthermore, the CPI value range for each water quality level was determined based on data obtained from 850 samples taken in the Pearl River Estuary. The remotely sensed CPIs were then transferred to water quality levels and appropriate maps were derived. The remotely sensed water quality level maps displayed a similar distribution of levels based on in situ investigation issued by the State Ocean Administration, China. This study demonstrates that remote sensing can play an important role in water quality assessment.