大亚湾水域营养盐的分布变化

本文通过对大亚湾水域溶解氧，氮、磷、化学耗氧量、盐度、ＰＨ等环境因子的调查，对该水域溶解氧的含量分布和季节变化进行了分析，同时，对湾内ＮＯ３－Ｎ、ＮＯ２－Ｎ、ＮＨ４－Ｎ及ＰＯ４－Ｐ的时空分布以及季节变化规律进行了讨论，并以氧的饱和度、ＰＨ、化学耗氧量、无机氮等单项指标和综合指标研究了该水域的富营养状况。     

Seasonal Variation of Environmental Variables and Phytoplankton Community Structure and Their Relationship in Liaodong Bay of Bohai Sea,China

In this paper, systematic studies on the changes in concentrations of the environmental factors and the net-phytoplankton community, and the relationship between them in the Liaodong Bay, Bohai Sea during 2013 are presented. The PCA results showed that higher levels of nutrients and dissolved heavy metals in the river-estuary-bay system were closely related to the river runoff. Since the influences of industrial and anthropogenic activities, the Liaodong Bay coastal areas are facing a huge environmental challenge of nutrients and heavy metal pollution. Net-phytoplankton community structure showed obvious seasonal succession, among which the dominant and (or) key species were the main factors affecting community structure change and stability. Under certain environmental conditions, the dominant species and (or) key species dominated the phytoplankton community structure succession. The Bio-ENV results suggested that the seawater temperature, nutrient, Cu, Pb, Zn, and Cd in Liaodong Bay are important environmental variables that affect the phytoplankton community structure. Anthropogenic activities have significantly contributed to the changes in concentrations of environmental factors and the net-phytoplankton community structure and stability, and the relationship between them.     

Migration of induced-infiltration stream water into nearby aquifer due to a transverse horizontal well in loess areas

Analysis of the migration paths of stream water introduced into a transverse horizontal well is important to better understand the interactions between streams and aquifers. This paper presents a method of using particle-tracking techniques to evaluate the transport of stream water that infiltrates through a transverse horizontal well that runs transverse to a stream and extends from the stream banks. By conceptualizing the horizontal well as a discrete pipe network, MODFLOW is coupled with the pipe flow equations that govern the movement of water in the horizontal well, and this coupled seepage-pipe flow model is used to calculate the transient groundwater flow field. MODPATH is then used to record the locations of each of the water particles from the interface between the stream and the aquifer. The path lines, travel times, influence zones and the production of infiltrated stream water are determined to depict the migration process. The results suggest that the infiltrated stream water that originates from different stream transects located upstream and downstream from the horizontal well has different migration characteristics, as does the infiltrated stream water coming from different locations on the same stream transect. Eventually, the pumpage of the horizontal well consists partly of the infiltrated stream water and groundwater inflow from the upstream model boundary. The groundwater enters the horizontal well through the two end segments of the horizontal well, and the infiltrated stream water enters the middle segment of the well. The pumped water is still a mixture of infiltrated stream water and groundwater, even if the pumping lasts for a long period. The hydrochemistry of the infiltrated stream water cannot be simply used to evaluate the hydrochemistry of the water pumped from a transverse horizontal well.     

Optimization and Field Application of CO2 Gas Fracturing Technique for Enhancing CBM Extraction

Since most coalfields in China are commonly characterized by high gas content and low permeability, there is an urgent need to improve coal seam permeability and further enhance coal bed methane (CBM) extraction efficiency. As an emerging fracturing technology, the CO₂ gas fracturing (CGF) technology has been widely used because of its advantages of low cost, environmental protection and high fragmentation efficiency. In order to improve the fracturing ability of CGF technique and optimize the release orifices of discharge head, computational fluid dynamics model was used in this paper to simulate the flow fields of dynamic pressure of gas jet released from the orifices with different structures and other geometrical parameters. The results show that the orifice structure has a great influence on the flow field of gas jet, but little influence on the magnitude of the dynamic pressure. Besides, the maximum dynamic pressure of gas jet linearly decreases with the increase in the number of release orifices. Based on a series of simulation results, the discharge head which has single group of orifices with structure c, diameter of 24 mm can be identified as the best choice for fieldwork. Then, two field experiments were conducted in Pingdingshan and Changping coal mines to evaluate the enhanced CBM extraction efficiency by CGF. The results indicate that the CGF can effectively create a large number of cracks in a large range around the fracturing borehole in the coal seam and further significantly improve the permeability. And the CBM extraction efficiency can be improved to a higher level from a lower level and maintained for a long time. Besides, the effective influence radii caused by CGF in Pingdingshan and Changping coal mines are 15.19 m and 12.5 m, respectively. Compared with other fracturing techniques, the CGF technique has a promising application prospect.

     

Large-scale seafloor stability evaluation of the northern continental slope of South China Sea

Abstract

With the continuous expansion of energy demand, the deep-water continental slope in the northern South China Sea has become one of the significant offshore oil and gas exploration regions. The frequent occurrence of marine geological hazards in this region, especially submarine landslides, can cause serious damage to engineering facilities. However, there have been few studies on the stability of the northern continental slope of the South China Sea; these studies mainly focused on a specific submarine slope or small-range evaluation, resulting in a lack of large-scale and quantitative understanding. Hence, considering the variation in the physical and mechanical properties of marine soils with depth, formulas for calculating the safety factor of submarine slopes by an infinite sliding model are established, and the factors affecting slope stability such as soil properties, slope gradient and horizontal seismic action are systematically investigated. Using GIS techniques, the terrain slope gradients and a historical seismic database of the northern South China Sea are obtained. Combined with soil mechanical parameters, a regional stability evaluation of the northern continental slope is carried out. Furthermore, the distribution of risk zones is given. On the whole, under strong seismic action, large-scale submarine slope instability occurs and must be highly considered when assessing risk. This achievement is of great significance to engineering sites, route selection and engineering risk assessment.     

海洋测量异常数据的检测

随着现代科学技术的发展和应用,海洋测量领域已先后推出了多种具有高分辨率和高采集率的新技术测量手段,如用于海底地形测量的多波束测深和机载激光测深系统。作为数据后处理软件系统的一个重要组成部分,我们急需寻求一种有效的异常数据探测方法来对采集到的海量数据进行质量检查和控制。与陆地测量相比较,海洋测量具有明显的动态效应,由于海水阻隔的原因,海洋测量不仅受大气的影响,而且受海水运动和海水物理性质的影响,因此     

Features of climate change and their effects on glacier snow melting in Xinjiang,China

The features of climate change and their effects on glacier snow melting in the past 50 years (1961–2010) in Xinjiang were studied. Regional climate data for 49 meteorological stations in the Tianshan Mountains and the northern and southern areas of Xinjiang were collected with the aid of techniques such as climatological statistical diagnosis, regional climate models, remote sensing, and geographic information system. The annual average temperature displayed a rising trend across the Tianshan mountainous area and both areas of Xinjiang. The trend was particularly apparent in winter and autumn with the rate of increase in the annual average minimum temperature being significantly higher than that of the maximum temperature. Rainfall also tended to increase in all three areas over the 50-year period, with the magnitude of change being highest in the mountainous area followed by northern Xinjiang and then southern Xinjiang. As a result of the rising temperatures, there was a negative material balance among the region's glaciers, of which the year 1982/1983 was the key year for the development of Tianshan mountain glacier snow. After this date, glacial ablation intensified with an annual change increase in average temperature of 1 °C, leading to a glacier material balance change of about 300 mm. To establish rainfall and temperature sequences for three regional climate change scenarios in the 2011–2050 period, we adopted the delta method using actual measurements during the 1961–2000 period against corrected data from rainfall and temperature simulations. All three scenarios indicated that temperatures will continue to increase, that the increase in rainfall may decrease in mountainous regions but will increase in the basin, and that the speed of glacial ablation in Xinjiang will continue to accelerate.     

典型盆地煤与油页岩共生成矿物质及古气候分析

选取煤与油页岩共生典型盆地山东黄县盆地、辽宁抚顺盆地、黑龙江依兰盆地和内蒙古金宝屯盆地,综合分析了其成矿物质特点,认为共生背景下煤岩中的低等动植物和油页岩中的高等植物均比单一矿种下含量高。这一规律可用于勘探、开发煤或油页岩单一矿种时预测其共生矿种存在的可能性。对古气候的分析表明,气候变换在一定程度上制约着煤与油页岩的共生模式,这种共生模式可为古气候研究提供一定依据,反之,通过古气候的变迁也可帮助勘探、开发共生背景下的煤与油页岩。     

气泡对流动注射峰形的影响及其干扰消除

研究了流动注射分析中气泡产生的原因、气泡形成吸收峰的原因及其峰的形状，并给出了气泡在不同温度下的吸收峰。讨论了消除流路体系中气泡的方法，指出用反压圈增大流路体系的压强是消除气泡干扰最简便的方法，并列举了用反压圈消除气泡的实例。