Genesis of the Sinian Solid Bitumen and its Significance for Hydrocarbon Accumulation in the Anyue Gas Field of the Sichuan Basin

正Objective Bitumen is generally associated with oil and gas,which was originally used as an indicator of hydrocarbon reservoirs.With the progress of organic geochemical measuring and testing techniques,bitumen,especially solid bitumen sampled from reservoirs,has been proved to be closely related to the evolution of hydrocarbon     

三峡工程对宜昌-监利河段水温情势的影响分析

三峡工程蓄水使得下游长江河道水温情势发生显著变化,并对下游生态环境产生重要影响。基于宜昌水文站14年的实测资料,采用纵向一维水温模型模拟分析了宜昌至监利300 km河道水温变化过程,探讨了不同蓄水期三峡工程下泄水温变化对坝下鱼类产卵场的影响程度。结果表明:①三峡工程蓄水后宜昌断面水温出现了平坦化及延迟现象,低温水和高温水效应明显;175 m蓄水期宜昌断面4月、12月,水温分别较蓄水前改变-4.3℃、3.7℃。②三峡工程的运行使得下游河道水气热交换量发生变化,但干流流量较大使得水温沿程恢复效果较弱;工程调蓄对坝下河段的影响占主导作用,三峡工程调蓄对监利断面4月、12月存在-3.2℃、3.0℃的温度影响。③三峡工程蓄水后,宜昌中华鲟产卵场冬季20.0℃的水温出现时间推迟1~4旬,监利四大家鱼产卵场春季18.0℃的水温出现时间推迟1~3旬,并随着蓄水位的抬升,推迟幅度逐渐加大。     

Magnetic Influences of Cement Dust on Soil in Industrial Area and Its Environmental Implications

To monitor environmental implications of cement dust on soil in industrial area, magnetic parameters and mineral compositions were measured by the samples of the cement dust, cement factory dustfall, cement, coal ash, topsoil of green space in the factory and topsoil outside the factory. Results showed that the major magnetic minerals in the samples were magnetite, the magnetic mineral particle size of cement dust, dustfall, cement and coal ash was coarse Multi-Domian (MD) and Pseudo-Single-Domain (PSD). As topsoil of green space in the factory and topsoil outside the factory were polluted by cement dust, their magnetic properties had been obviously changed; the concentration of magnetic minerals elevated and particle size became coarser. The magnetic parameters (χ_fd,χ_ARM/χ,χ_ARM/SIRM) value can reflect the pollution level of the soil, the lower its value was, the more serious soil was polluted. X-ray diffraction results showed that the mineral compositions of the topsoil of green space in the factory and topsoil outside the factory were quartz and calcite, which were the same as cement dust. Magnetic parameters combination characteristics of topsoil can monitor the soil environmental changes in cement industry area.     

The North Atlantic Oscillation (NAO) and Europe Blocking and Their Impacts on Extreme Snowstorms: A Review

Large-scale, low frequency modes such as the North Atlantic Oscillation(NAO)and blocking, have an important modulation on the northern hemisphere weather and climate. In this paper, the physical mechanism studies on inter-decadal and decadal variability of NAO and blocking were summarized. The relationship between NAO regime transitions and the interannual variability of NAO in winter during was examined by using a statistical approach. The time-space relationship between NAO and European blocking were discussed. Based on two extreme cold and snowstorm events, the impacts on local weather especially the extreme events within the life cycle (two weeks) of the NAO and blocking were further examined. It was found that the frequently occurrence of the Eurasian extreme snowstorm was closely related to the special combination of NAO and blocking regime. In addition, the development of theoretical modes for NAO and blocking was discussed and issues that remain to be solved were proposed.     

长江三峡地区的夷平面在宜昌地区白垩纪—第四纪沉积物中的反映

通过对湖北宜昌地区白垩纪—第四纪沉积演化的研究,发现存在3个明显的沉积旋回,每个旋回由下部颗粒粗大的砾石层和上部颗粒较细小的粉砂-泥质层组成。3个沉积旋回对应了宜昌以西三峡地区3期构造演化旋回,同时反映了三峡地区3期夷平面的存在。结合前人研究结果、古生物化石和对第四系善溪窑组的测年数据,认为3期夷平面形成时代分别为:鄂西期夷平面形成于白垩纪晚期—古近纪的始新世,山原期夷平面形成于上新世—早更新世初,云梦期夷平面形成于早更新世末—中更新世早期。     

Spatial distribution of crustaceans associated with shallow soft‐bottom habitats in a coral reef lagoon

The ecology and diversity of the shallow soft‐bottom areas adjacent to coral reefs are still poorly known. To date, the few studies conducted in these habitats dealing with macroinvertebrate fauna have focused on their abundance spatial patterns at high taxonomic levels. Thus, some aspects important to evaluate the importance and vulnerability of these habitats, such as species diversity or the degree of habitat specialization, have often been overlooked. In this study we compared the crustacean assemblages present in four different habitats at Magoodhoo Island coral reef lagoon (Maldives): coral rubble, sandy areas and two different seagrass species (Thalassia hemprichii and Cymodocea sp.). Forty‐two different crustacean species belonging to 30 families and four orders were found. ‘Site’ was a significant factor in all of the statistical analyses, indicating that tropical soft‐bottom habitats can be highly heterogeneous, even at a spatial scale between tens and hundreds of meters. Although traditionally it has been considered that seagrass beds host greater species diversity and abundance of organisms than adjacent unvegetated habitats, no differences in the univariate measures of fauna (abundance of organisms, number of species and Shannon diversity) were observed among habitats. However, sandy areas, coral rubble and seagrass beds exhibited different species composition of crustacean communities. The percentage of taxa considered as potential habitat specialists was 27% and the number of species exclusively occurring in one habitat was especially high in seagrass beds. Thus, degradation of this vegetated habitat would result in a great loss of biodiversity in tropical shallow soft‐bottom habitats.     

Hydrographic Vertical Separation Surfaces (HyVSEPs) for the Tidal Waters of Canada

Since the advent of Global Navigation Satellite Systems, it has been possible to perform hydrographic survey reductions through the ellipsoid, which has the potential to simplify operations and improve bathymetric products. This technique requires a spatially continuous separation surface connecting chart datum (CD) to a geodetic ellipsoid. The Canadian Hydrographic Service (CHS), with support from the Canadian Geodetic Survey, has developed a new suite of such surfaces, termed Hydrographic Vertical Separations Surfaces, or HyVSEPs, for CD and seven tidal levels. They capture the spatial variability of the tidal datum and levels between tide gauges and offshore using semiempirical models coupling observations at tide stations with relative sea-level rise estimates, dynamic ocean model solutions, satellite altimetry, and a geoid model. HyVSEPs are available for all tidal waters of Canada, covering over seven million square kilometers of ocean and more than 200,000 kilometers of shoreline. This document provides an overview of the CHS's modeling approach, tools, methods, and procedures.

The HyVSEP for CD defines the new hydrographic datum for the tidal waters of Canada. HyVSEPs for other tidal levels are fundamental for coastal studies, climate change adaptation and the definition of the Canadian shoreline and offshore boundaries. HyVSEPs for inland waters are not discussed.     

Crustacean decapod assemblages associated with fragmented Posidonia oceanica meadows in the Alboran Sea (Western Mediterranean Sea): composition,temporal dynamics and influence of meadow structure

The decapod assemblage associated with a Posidonia oceanica meadow located near its western limit of biogeographic distribution was studied over an annual cycle. Fauna samples were taken seasonally over a year (five replicates per season) in two sites located 7 km apart, using a non‐destructive sampling method (airlift sampler) for the seagrass. The dominant species of the assemblage, Pisidia longimana, Pilumnus hirtellus and Athanas nitescens, were associated with the protective rhizome stratum, which is mainly used as a nursery. The correlations between decapod assemblage structure and some phenological parameters of the seagrass shoots and wave height were negative or null, which reflects that species associated with the rhizome had a higher importance than those associated with the leaf stratum. The abundance and composition of the decapod assemblage as well as the ecological indexes displayed a seasonality trend with maximum values in summer‐autumn and minimum in winter‐spring, which were related to the seawater temperature and the recruitment periods of the dominant species. The spatial differences found in the structure and dynamics of the assemblages may be due to variations in the recruitment of the dominant species, probably as a result of the influence of local factors (e.g. temperature, currents) and the high dispersal ability of decapods, together with the patchy configuration and the surrounding habitats. The studied meadows are fragmented and are integrated within a mosaic of habitats (Cymodocea nodosa patches, algal meadows, rocky and sandy bottoms), which promotes the movement of individuals and species among them, maintaining a high species richness and evenness.     

长江河口北槽河道悬沙絮团特性及其影响因素研究

利用多种先进室内外测量仪器进行河口现场观测和室内电镜扫描获得相关资料,对长江河口北槽河道细颗粒泥沙絮凝的水沙环境、絮团的微观形态结构、絮团的粒径组成及其主要影响因素进行了综合分析和讨论。结果表明,北槽河道具有非常适宜细颗粒泥沙絮凝的潮流、盐度、含沙量和悬沙颗粒粒径等基本环境条件。北槽河道悬沙絮团形态多样,主要包括松散状絮团、蜂窝状絮团和密实状絮团。絮团主要由细粉砂和黏土类细颗粒泥沙组成,表面多粗糙不平,结构或密或疏。絮团粒径变化与潮周期动力过程密切相关,具有周期性变化特征。涨、落憩时絮团粒径较大,涨、落急时絮团粒径较小。絮团粒径涨憩大于落憩,小潮大于大潮。垂向上,絮团粒径由表层至底层逐渐增大。周期性潮流流速对北槽河道悬沙絮团粒径变化起到了控制作用。北槽细颗粒泥沙絮凝作用,是导致疏浚航道发生回淤的主要原因之一。     

低分子质量褐藻寡糖的高效酶法制备及其抗氧化活性评价

褐藻寡糖具有多种生理活性,本研究通过酶解与分级条件的优化,获得了低分子质量褐藻寡糖的酶法制备工艺,并在体外模型上评价了不同分子质量组分的抗氧化活性。结果表明,优化后的褐藻寡糖制备条件为:底物浓度1.20%,酶底比4.35 U/mg,酶解时间4 h。进一步采用乙醇沉淀和超滤分离后,获得了重均分子质量分别为0.84、1.40、2.25和34.56 k Da的4种组分,其得率分别为50.82%、5.15%、11.48%和12.00%。各组分均具有一定的还原能力,可有效清除DPPH和羟自由基,其中低分子质量组分A的抗氧化活性最为显著,其清除羟自由基的能力与维生素C相近。