On the Conversion of Antarctic Ice-Mass Change to Sea Level Equivalent

This technical note aims to provide a quick reference and some computational examples for the conversion between Antarctic ice-mass changes and global sea level equivalent (SLE) changes using a few assumptions that computationally simplify this complex problem and that acknowledge gaps in our knowledge of the Antarctic environment. A number of factors involved in the conversion process are discussed, and the sensitivity of the conversion result to certain aspects is analyzed. It was found that the global ocean area calculated from a recently improved global shoreline dataset has little impact on the uncertainty of the SLE estimation. SLE estimation using satellite gravity observations, such as those by GRACE, are sensitive to glacial isostatic adjustment (GIA) models. One more important result from the computation is that the effective density of the volume that is gained or lost during mass change may greatly affect the outcome of the conversion if it differs greatly from the actual density of the firn/ice layers. Finally, a table of computational examples is provided for reference under some assumptions for simplifying the computation.     

A Lagrangian particle random walk model for simulating a deep-sea hydrothermal plume with both buoyant and non-buoyant features

This paper presents a computational model of simulating a deep-sea hydrothermal plume based on a Lagrangian particle random walk algorithm. This model achieves the efficient process to calculate a numerical plume developed in a fluid-advected environment with the characteristics such as significant filament intermittency and significant plume meander due to flow variation with both time and location. Especially, this model addresses both non-buoyant and buoyant features of a deep-sea hydrothermal plume in three dimensions, which significantly challenge a strategy for tracing the deep-sea hydrothermal plume and localizing its source. This paper also systematically discusses stochastic initial and boundary conditions that are critical to generate a proper numerical plume. The developed model is a powerful tool to evaluate and optimize strategies for the tracking of a deep-sea hydrothermal plume via an autonomous underwater vehicle (AUV).     

有孔虫初房特征变化在珠江三角洲晚全新世东亚夏季风降雨研究中的应用

研究中国降雨格局变化对理解东亚夏季风演化意义重大。本文分析了珠江三角洲柱状样ZJK03-Z中浅水底栖有孔虫常见种Rotalidium annectens的平均初房大小、微球型/显球型比值和壳体δ18O值,以及底栖有孔虫组合中瓷质壳的百分含量,探讨它们对由夏季风降雨引起的河口水体盐度变化的响应,得到了珠江三角洲3114—1260a BP季风降雨的强度变化,识别出了这期间14次季风降雨减少的偏干期。与南美洲Cariaco海盆的钛含量记录对比,二者一致的结果表明,珠江三角洲晚全新世的东亚夏季风降雨与热带辐合带(ITCZ)的南北移动密切相关:夏季风降雨减少,对应于ITCZ纬度位置的南移。     

南大西洋沉积物中多环芳香化合物的组成特征研究

10 samples of sediments obtained from the South Mid-Atlantic Ridge were measured for the abundances and distributions of polycyclic aromatic compounds(PAHs). The total concentrations of PAHs(∑PAHs) ranged from 2.768 to 9.826 μg/g dry sediment. The ∑PAHs was higher in sample 22V-TVG10 and sample 26V-TVG05 which were close to hydrothermal fields, with the lowest value in sample 22V-TVG14 which was farthest from hydrothermal fields, suggesting a probable hydrothermal origin of ∑PAHs of samples. Approximately nine kinds of PAHs were identified, and low molecular mass tricyclic and tetracyclic aromatic compounds were predominant in the samples. The concentrations of fluoranthene which were typical as hydrothermal alteration compounds were the highest among PAHs with dry weight between 0.913–3.157 μg/g. The phenanthrene homologue was most abundant in the samples, and the ratios between parent phenanthrene and methylphenanthrene which probably reflected the degree of hydrothermal alteration ranged from 0.097 to 1.602. The sample 22V-TVG10 possessing a maximum ratio value showed the intense influence of the hydrothermal alteration on this sample, which might further imply that PAHs in sediments were mainly derived from the hydrothermal alteration.     

海洋浮游微食物网结构及其影响因素

微食物环是海洋生态系统中重要的物质和能量过程,是传统食物链的有效补充。微食物环研究是当前海洋生态学研究的热点之一,但对其结构的系统研究较少,海洋微食物网结构在2000年才被Garrison提出。尽管微食物网各个类群的丰度在不同海洋环境中有相对变化,但是这些变化都处于一定的范围之内,其丰度结构约为纤毛虫10 cell ml-1、鞭毛虫103 cell ml-1、微微型真核浮游生物104 cell ml-1、蓝细菌104-5 cell ml-1、异养细菌106 cell ml-1、病毒107 particle ml-1。海洋浮游食物链中捕食者和饵料生物粒径的最佳比值为10:1,实际研究中该比值会略低,例如纤毛虫与其饵料的粒径比值为8:1,鞭毛虫为3:1。Pico和Nano浮游植物的丰度比（Pico:Nano）是研究微食物网结构的指数之一,该指数具有不受研究尺度影响的优点,可用于研究区域性和全球性微食物网结构。近年来,学者们从多角度对海洋微食物网的结构开展了研究,不同海区微食物网各类群丰度、生物量的时间和空间变化研究有很多报道,微食物网的结构可受空间、季节、摄食、营养盐等多种因素影响。在对不同空间微食物网的研究中,学者往往研究不同物理性质的水团中各类群生物丰度的不同,以此来表征微食物网结构的不同;同一海区微食物网结构的季节变化也是使用各个类群丰度和生物量的变化来表示,该变化主要受水文环境因素影响。摄食者对微食物网各类生物的影响通过三种途径：1. 中型浮游动物摄食;2. 中型浮游动物摄食微型浮游动物,通过营养级级联效应影响低营养级生物;3. 中型浮游动物通过释放溶解有机物、营养盐影响细菌和低营养级生物。浮游植物通过产生化感物质和溶解有机物影响微食物网结构,而营养盐的浓度及变化则可以对微食物网产生直接或间接影响。     

中国南方二叠纪古海洋锶同位素演化

本文以贵州罗甸沫阳二叠系剖面为研究对象，通过对海相碳酸盐岩的锶同位素组成变化的研究，探讨了中国南方二叠纪古海洋锶同位素组成特点、演化及其地质意义。     

孔隙衬里绿泥石的成因及对储层性能的影响

孔隙衬里绿泥石发育的砂岩大多属于优质储层,前人将其归功于绿泥石对孔隙的保护作用。按照孔隙衬里绿泥石形成的铁质来源,可划分为同沉积黏土膜转化型、富铁镁物质溶蚀再结晶型和转化与直接结晶混合型3种类型。通过国内外富孔隙衬里绿泥石砂岩实例的对比研究表明,孔隙衬里绿泥石可以通过抑制自生石英生长、提高抗压实能力、指示早期碱性溶蚀发育程度和堵塞孔喉等4种方式影响储层性能,且不同成因的孔隙衬里绿泥石对储层性能影响方式不同,同一成因绿泥石在不同成岩阶段的影响方式也不同。中成岩A期以前,转化型孔隙衬里绿泥石通过占据孔喉和提高抗压能力影响储层,而溶蚀结晶型孔隙衬里绿泥石主要指示火山物质发生碱性溶蚀的程度;只有砂岩成岩阶段达到中成岩B期以后,孔隙衬里绿泥石对石英生长的抑制作用才得到充分体现。     

城市地下管线信息化建设框架研究

目前,我国各城市相继展开地下管线普查、地下管线信息系统的建设工作,力求建立科学、准确、完整、动态的综合管线信息管理系统,但也都普遍存在一些问题。本文针对管线信息化过程中普遍存在的这些问题,提出站在城市的高度,统筹规划管线信息系统的建设工作。并通过对现代城市发展过程中城市管线信息需求的分析,给出了城市地下管线信息化建设的一种框架。     

北极冰下水声通信中改进的最小均方/四次方直接自适应均衡器

本文提出了一种适用于北极冰下水声通信的最小均方/四次方直接自适应均衡器（LMS/F-DAE）。它能处理基带复信号,与LMS相比,具有更好的均衡效果。考虑到均衡器的稀疏特性,在其代价函数中加入自适应范数（AN）作为约束。它能根据均衡器系数的大小自适应变化：对于小系数,此约束项存在以加快收敛速度;对于大系数,此约束项不存在以减小均衡误差。利用第九次中国北极科学考察得到的实验数据验证AN-LMS/F-DAE的性能。结果表明,与传统的LMS/F-DAE相比,AN-LMS/F-DAE能提升均衡器的稀疏性且均衡性能更优。