大型浅水湖泊藻类模型参数敏感性分析

选取太湖作为典型湖泊在之前研究基础上建立藻类模型,对模型中与藻类有关的40个参数进行拉丁超立方抽样,并使用区域敏感性分析方法和普适似然不确定性分析方法进行敏感性分析.结果表明:在所选的40个参数中,有7个参数是敏感的参数,对模拟的结果影响较大.在藻类生长、基础代谢、牧食和沉降4个藻类变化过程中藻类生长的敏感参数最多,影响最大;在藻类生长项中,叶绿素的消光系数是藻类生长光照限制中的最敏感参数,而最低适宜生长温度及其对藻类生长的影响系数则是温度限制中的敏感参数;并且不同湖区的不确定性在不同时间差异明显,对于藻类低浓度湖区和藻类暴发期的模拟需要加以关注.     

Total organic carbon fluxes of the Red River system (Vietnam)

Riverine transport of organic carbon from terrestrial ecosystems to the oceans plays an important role in the global carbon cycle. The Red River is located in Southeast Asia where river discharge, sediment loads and fluxes of elements (carbon, nitrogen and phosphorus) associated with suspended solids have been dramatically altered over past decades as a result of reservoir impoundment and land use, population, and climate change. Dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations were measured monthly at four stations of the Red River system from January 2008 to December 2010. The results reveal that POC changed synchronically with total suspended solids (TSS) concentration and with the river discharge, whereas no clear trend was observed for DOC concentration. The mean value of total organic carbon (TOC = DOC + POC) flux in the delta of the Red River was 31.5 × 10¹³ ± 4.0 × 10¹³ MgC.yr^?1 (range 27.9–35.8 × 10¹³ MgC.yr^?1 which leads to a specific TOC flux of 2012 ± 255 kgC.km^?2.yr^?1 during this 2008–2010 period. About 80% of the TOC flux was transferred to the estuary during the rainy season as a consequence of the higher river water discharge. The high mean value of the POC:Chl‐a ratio (1585 ± 870 mgC.mgChl‐a^?1) and the moderate C:N ratio (7.3 ± 0.1) in the water column system suggest that organic carbon in the Red River system is mainly derived from erosion and soil leaching in the basin. The effect of two new dam impoundments in the Red River was also observable with lower TOC fluxes in 2010 compared with 2008. Copyright © 2017 John Wiley & Sons, Ltd.     

The geological characteristics of the large-and medium-sized gas fields in the South China Sea

By the end of 2019, more than 220 gas fields had been discovered in the South China Sea. In order to accurately determine the geological characteristics of the large-and medium-sized gas fields in the South China Sea, this study conducted a comprehensive examination of the gas fields. Based on the abundant available geologic and geochemical data, the distribution and key controlling factors of the hydrocarbon accumulation in the South China Sea were analyzed. The geological and geochemical features of the gas fields were as follows:(1) the gas fields were distributed similar to beads in the shape of a "C" along the northern, western, and southern continental margins;(2) the natural gas in the region was determined to be composed of higher amounts of alkane gas and less CO_2;(3) the majority of the alkane gas was observed to be coal-type gas;(4) the gas reservoir types included structural reservoirs, lithologic reservoirs, and stratigraphic reservoirs, respectively;(5) the reservoir ages were mainly Oligocene, Miocene, and Pliocene, while the lithology was mainly organic reef, with some sandstone deposits; and(6) the main hydrocarbon accumulation period for the region was determined to be the late Pliocene-Quaternary Period. In addition, the main controlling factors of the gas reservoirs were confirmed to have been the development of coal measures, sufficient thermal evolution, and favorable migration and accumulation conditions.     

A seismic interpolation and denoising method with curvelet transform matching filter

A new seismic interpolation and denoising method with a curvelet transform matching filter, employing the fast iterative shrinkage thresholding algorithm (FISTA), is proposed. The approach treats the matching filter, seismic interpolation, and denoising all as the same inverse problem using an inversion iteration algorithm. The curvelet transform has a high sparseness and is useful for separating signal from noise, meaning that it can accurately solve the matching problem using FISTA. When applying the new method to a synthetic noisy data sets and a data sets with missing traces, the optimum matching result is obtained, noise is greatly suppressed, missing seismic data are filled by interpolation, and the waveform is highly consistent. We then verified the method by applying it to real data, yielding satisfactory results. The results show that the method can reconstruct missing traces in the case of low SNR (signal-to-noise ratio). The above three problems can be simultaneously solved via FISTA algorithm, and it will not only increase the processing efficiency but also improve SNR of the seismic data.     

北京城区大气混合层内臭氧垂直结构特征的初步分析——基于臭氧探空

本文利用2013年6月至2015年10月北京南苑观象台两年多午后臭氧探空资料,初步分析了北京城区大气混合层内臭氧浓度的垂直分布规律以及典型天气条件下大气边界层臭氧的变化特征.主要结果有：（1）季节平均而言,地表至对流层中部（8 km）的臭氧浓度在夏季最高,冬季最低,相差50~130 μg·m^-3,最大差异在边界层.总体而言,对流层臭氧浓度随高度有比较缓慢的增加,但是边界层内臭氧浓度的垂直结构随季节有比较大的差异：夏季混合层中部存在一个臭氧浓度极大值,这与夏季比较强的光化学生成臭氧有关;而在冬季地面臭氧浓度很低,平均值小于40 μg·m^-3,说明冬季地面是臭氧很强的汇.（2）臭氧浓度季节内变率的季节差异也十分明显,夏季最大、冬季最小.季节内变率在从边界层向自由对流层过渡区域最小（夏季为24 μg·m^-3,冬季仅为10 μg·m^-3）,在边界层内变率较大,夏季可达64 μg·m^-3（冬季为30 μg·m^-3）,这也说明边界层化学过程明显影响臭氧浓度的变化.（3）我们从所有白天样本中严格筛选了部分混合层样本,并把臭氧浓度在由混合层向自由大气过渡时的垂直分布分成了三类,即臭氧浓度随高度增大（Ⅰ型）、减小（Ⅱ型）以及基本稳定不变（Ⅲ型）;臭氧垂直结构类型有明显的季节特征,夏季主要是Ⅱ型,而冬季则以Ⅰ型为主.（4）此外,我们还针对一些典型天气过程（强风、静稳雾天和PM_2.5污染）边界层内臭氧的变化特征进行了分析,结果表明：强风切变产生的机械对流引起的充分混合,有利于高层臭氧向低层输送,使得混合层内臭氧浓度的垂直梯度明显减小,同时混合层高度较高,达3 km以上;在高湿度静稳天气控制下,大气混合层较稳定,对北京上空污染物的垂直扩散十分不利：颗粒物浓度升高,削弱到达近地层的太阳辐射,从而降低臭氧的生成效率,混合层内臭氧浓度与混合层厚度都处于较低水平.     

心外膜及心周脂肪体积与颈动脉粥样斑块的关系

目的:探讨CT平扫测量心外膜及心周脂肪体积与颈动脉粥样硬化斑块的关系。方法:选取开滦集团高管健康查体职工475例,均接受胸部CT平扫检查,测量相应心外膜及心周脂肪体积。根据颈动脉彩超结果将其分为有斑块组165例和无斑块组310例,并进一步以BMI (kg/m2)“24”、“28”分别作为超重、肥胖的界限,将其分为正常体重组129例、超重组258例和肥胖组88例。分别研究正常体重组、超重组和肥胖组中有无颈动脉斑块者的心外膜及心周脂肪体积的相关性。结果:正常体重组有颈动脉斑块者45例,无斑块者84例;超重组有斑块者86例,无斑块者172例;肥胖组有颈动脉斑块者34例,无斑块者54例,3组中有颈动脉斑块的心外膜及心周脂肪体积均大于无颈动脉斑块的,差异有统计学意义(P<0.05)。结论:心外膜及心周脂肪体积随着肥胖程度的增加而增加,排除BMI因素,心外膜及心周脂肪体积与颈动脉粥样硬化斑块形成具有较强的相关性。      

Major advances in studies of the physical geography and living environment of China during the past 70 years and future prospects

The natural environment provides material essentials for human survival and development. The characteristics,processes, regional differentiation and forcing mechanisms of the elements of the natural environment(e.g. geomorphology,climate, hydrology, soil, etc.) are the main objects of research in physical geography. China has a complex natural environment and huge regional differentiation and therefore it provides outstanding reserach opportunities in physical geography. This review summarizes the most important developments and the main contributions of research in the physical geography and human living environment in China during the past 70 years. The major topics addressed are the uplift of the Tibetan Plateau and the evolution of its cryosphere, the development of fluvial systems, the acidification of the vast arid region of the Asian interior, variations in the monsoon and westerly climate systems on multiple timescales, the development of lakes and wetlands, the watershed system model, soil erosion, past human-environment interactions, biogeography, and physical geographic zonality. After briefly introducing international research developments, we review the history of research in physical geography in China, focusing on the major achievements and major academic debates, and finally we summarize the status of current research and the future prospects. We propose that in the context of the national demand for the construction of an ecological civilization, we should make full use of the research findings of physical geography, and determine the patterns and mechanisms of natural environmental processes in order to continue to promote the continued contribution of physical geography to national development strategies, and to further contribute to the theory of physical geography from a global perspective.     

人类工程活动的生态环境效应--以大连市金州区七顶山乡一带生态环境演变为例

简要介绍了人类工程活动:人工开垦水田、建造水坝和超采地下水为大连市供水,导致生态环境一系列演变,从自然生态系统变为人工生态系统,同时导致了次生地质灾害:海水倒灌入侵,污染地下水源,引起了C l-浓度从50 m g/L上升到250~500 m g/L,最高可达1 000 m g/L,超过国家标准;土地沙化和产生的流动沙丘,它们危害农业生产和农舍。     

甘肃北山南部活动断裂的发现及其区域构造意义

在河西走廊北侧、 北山南缘新发现属于不同断裂系统的两条晚第四纪活动断裂,分别称之为旧井-板滩断裂和俄博庙断裂.其中,旧井-板滩断裂长约28 km,距玉门市约55 km,由4条分支断裂组成,呈复杂的"Y"字形分布.总体走向北东40°～50°,倾向北西,倾角60°～70°,控制了西侧两个晚新生代盆地的发育.俄博庙断裂长约1...     

东海陆架西北部地貌分类及沉积环境演变研究

根据多次海洋调查的多波束、表层沉积物资料及中法合作海洋地质调查的浅地层剖面资料,对东海陆架西北部的地貌进行详细分类,探讨该区环境演化规律。分析结果表明,该区存在潮流沙脊,潮流冲刷槽、暗礁等多种地貌形态;该区发育多期潮流沙脊,反映了本区晚更新世以来经历了多次海进和海退过程。