乐山市盐气资源开发中应重视的一些问题

总结乐山市开发利用威西岩盐矿和犍为县麻柳场天然气出现诱发地震活动的特点,分析其形成原因,提出在威西岩盐矿和天然气开发区建立高质量的地震监测台网,为科学研究提供更多系统可靠的基础观测资料,深入开展盐气资源开发与诱发地震活动关系的研究,为制定科学合理的开发规划提供依据;开展跨行业科学研究,搞好盐气资源综合开发利用;切实抓好重大建设项目的抗震设防管理和各类设备的抗震安全,提高抗震防灾能力,加强领导与协调,共同做好盐气资源的开发利用。     

A Free Boundary Problem Related to the Location of Volcanic Gas Sources

A mathematical model of general gas emitting systems is derived, and a sample of relevant mathematical results is offered. The present paper indicates that shallow subsurface gas sources in typical volcanic areas can be located if appropriate physico-chemical measurements are made on the Earths surface and put to use.     

Linking dynamic elastic parameters to static state of stress: toward an integrated approach to subsurface stress analysis

Stress is the most important parameter to understand basin dynamics and the evolution of hydrocarbon systems. The state of stress can be quantified by numerical geo-mechanical modelling techniques. These techniques require static elastic parameters of the rocks as input, while tectonic and gravitational forces are given as explicit boundary conditions to compute the local state of stress at different scales. We developed a technique to determine the density and elastic constants at seismic frequencies using full Zoeppritz inversion on angle-dependent seismic reflection data. The dynamic elastic parameters as obtained from seismic data differ from their static equivalents, which are necessary to determine the static state of stress. The dynamic elastic parameters are related to their static equivalents through experimentally obtained relations. In these rock-physics experiments, the static and dynamic elastic parameters are measured simultaneously during different external loading conditions. The experiments used here are all carried out in a tri-axial pressure machine under equal axial stresses. Then pre-stack seismic data analysis in combination with the relation between the static and dynamic elastic parameters, from the rock-physics experiments, provides the input parameters for geo-mechanical modelling.     

民乐—山丹地震地下流体异常场特征及其成因分析

介绍了2003年10月25日民乐-山丹MS6.1地震前地下流体异常场的时空特征及其演化,分析了地下流体异常场的成因。研究结果表明,民乐-山丹地震地下流体前兆场具有异常时间长、异常项次多、异常范围大的特征,其原因是受青藏块体整体构造和地震活动水平增强以及2001年11月14日昆仑山口西8.1地震的影响。     

Mesoscalic estimation of nitrogen discharge via drainage systems

A complex approach has been developed for estimating mesoscalic nitrogen discharges via drainage systems using spatial information about land use, drainage areas, nitrogen balances and soil and site characteristics. Determining the total drainage area involves certain difficulties for larger areas, as on the one hand, the available databases are incomplete, and on the other hand the localisation and digitalisation of large subsurface drainage areas is a very time-consuming process. Knowledge of the history and causes of drainage systems in landscapes is required. To solve this problem a method has been developed to calculate the drainage areas for large catchments. In order to obtain a complete data set of subsurface drainage areas, representative areas were selected to enable the proportion of subsurface drainage area to be determined for various soil and site characteristics. These proportions were extrapolated to the entire area and the approach tested in the Mulde River Catchment Area in Germany.The rate of drained arable land is about 25.2% of the total area, which can be broken down into grassland (19.0%) and arable land (27.4%). The results differ for sandy soils with up to 8% drained areas and 57.8% for stagnant soils. This shows that the proportion of drained land is highly dependent on the nature of the soil in the catchment area, which has profound implications for approaches to nitrogen modelling.Average nitrogen discharge for the whole catchment area via drainage water was 33 kg ha⁻¹ yr⁻¹ in the 1980s and 10 kg ha⁻¹ yr⁻¹ in the 1990s. The nitrogen discharge varies from one soil type to another: in regions with sandy substrate (11,900 ha) discharge was 34 kg ha⁻¹ yr⁻¹ in the 1980s (14 kg ha⁻¹ yr⁻¹ in the 1990s), while in areas with loess lessivé soils (89,200 ha) it was about 26 kg ha⁻¹ yr⁻¹ in the 1980s (9 kg ha⁻¹ yr⁻¹ in the 1990s). The reduction can be explained by the complete change in farming strategy since the demise of the former German Democratic Republic (GDR).The approach shown is well suited to future model approaches on a regional scale. By creating and integrating new data sets derived from modern GIS operations the approach reduces the uncertainty of water and nitrogen modelling. This gives us a better understanding of nitrogen discharges into surface and groundwater and temporal discharge dynamics. The discharge data are highly valuable to predict environmental protection measurements for streams, lakes, coastal waters and groundwaters.     

西安城市地温与气温变化初步分析

地下浅层地温和近地表空气温度存在着必然的内在联系,地面温度变化的信息随着时间推移向下传播并叠加到稳态地温场上,因此通过对现今地温剖面的分析可以重建过去地面温度变化的历史。为了研究西安地区地下和地上的温度变化,本文在西安开展了钻孔温度测量,获得了16个钻孔的地温剖面,同时收集整理了西安气象站1951～2010年气温数据。对1951～2010年气温数据进行回归分析得到西安地区年平均气温、年平均最高气温和最低气温增温率分别为3.71 ℃/100a、2.03 ℃/100a和5.14 ℃/100a,均高于全国和全球平均水平,其中1986～2010年间平均气温增温更是显著,达到9.01 ℃/100a。从钻孔测温曲线中筛选出西安城郊6个传导型地温剖面进行分析,结果表明西安地区钻孔温度记录的地面温度变化趋势与气象台记录的气温变化趋势基本吻合。根据利用钻孔温度剖面下段回归分析得到的地表稳态温度和地温梯度以及25年间西安地区平均气温增温率推算得到钻孔理论地温剖面与实测地温数据总体上具有较好的一致性。对实测地温数据的进一步精确拟合分析显示,西安城郊6个选定的钻孔所在区域地面温度变暖分别起始于20年、24年、26年、28年、30年和30年前,对应的地表增温幅度分别为0.4 ℃、0.72 ℃、2.18 ℃、4.2 ℃、2.4 ℃和2.4 ℃。市区和周边郊区钻孔所在区域在增温幅度上存在明显的差异,市区增温强度明显高于郊区,而城郊结合部介于两者之间。     

现代海底热液微生物群落及其地质意义

现代海底黑烟囱周围生活着密集的生物群落,它们一般以黑烟囱喷口为中心向四周呈带状分布。热液生态系统的初级生产者嗜热细菌和古细菌,其初级能量来源于地球深部上升喷出流体提供的化学能,它们氧化热液中硫化物（如H2S、FeS）和甲烷获得能量,还原CO2制造有机物,而不依赖光合作用。作为食物链源头的细菌类和古细菌类与其他动物有2种生存关系:①直接作为其他动物的食物;②与其他动物之间的共生关系。这些嗜热微生物不仅依存于海底热液活动,同时在热液成矿作用中起着重要的作用。它们可能来源于地下深部生物圈,海底黑烟囱是研究深部生物圈的窗口,对其周围嗜热微生物的研究,对于理解生命起源和生物成矿都有重要的理论意义。     

Advances in research on earthquake fluids hydrogeology in China:a review

Monitoring of subsurface fluid （underground fluid） is an important part of efforts for earthquake prediction in China. The nationwide network, which monitors groundwater level, water temperature, and radon and mercury in groundwater, has been constructed in the last decades. Large amounts of abnormal fluid changes before and after major earthquakes have been recorded, providing precious data for research in earthquake sciences. Many studies have been done in earthquake fluid hydrogeology in order to probe the nature of the earthquake. Much progress in earthquake fluid hydrogeology has been made in the last decades. The paper provides a review of the advances in research on earthquake fluid hydrogeology over the last 40 years in China. It deals with the following five aspects： （1） an introduction to the development history of monitoring networks construction; （2） cases of different subsurface fluid changes recorded before some major earthquakes which occurred in the last decades; （3） characteristics of subsurface fluid changes following major earthquakes; （4） mechanism of subsurface fluid changes before and following earthquakes; （5） application of earthquake fluids in the hydrogeology field.     

Research Status and Prospect of the Subsurface Hydrology and Ecological Effect in Arid Regions

Centering on the scientific problems faced by subsurface hydrology in arid regions and ecological effect, the urgency of national ecological civilization and the Belt and Road construction towards the research of groundwater discipline, this article analyzed the formation and evolution mechanisms of groundwater and studied the groundwater function of arid regions. Based on the analysis and research, this article discussed domestic and overseas research status, existing problems and developing trend from six aspects, raised key and scientific problems which urgently need to be addressed, aiming at the existing bottlenecks of subsurface hydrology and ecological effect in arid regions and national requirement, so as to make some contribution to the innovative development of China’s groundwater science and national economic construction.     

2004~2006年奄美大岛以东的琉球海流

基于2004~2006年12个航次的水文资料,用逆方法计算得到了奄美大岛以东AE断面琉球海流的流速和体积流量.再次证实琉球海流具有较稳定的次表层流核结构,流核位于110～600 m深度,并沿AE线分布于27.2°～28.2°N,流核的最大流速为15.1～80.0 cm·s-1. 12个航次的平均流速断面显示了一个完整的次表层流核,其流核的最大流速为21.3 cm·s-1, 流核的垂直和水平尺度分别为800 m 和 30 km. 观测结果表明,2004~2006年之间,琉球海流冬季、春季、夏季、秋季和年平均的流量分别为10.9,10.1,5.9,23.9和12.7×106 m3·s-1,秋季最强,夏季最弱.日本以南黑潮净流量为52.7×106 m3·s-1, 其中源于吐噶喇海峡黑潮和琉球海流的流量平均比为0.40.