美国东南部大陆边缘的天然气水合物利用宽角地震资料进行全波形约束和走时反演

利用BSR已完成美国东南边缘大约50000km2的地区编图，并已证实可能与大量天然气水合物有关。1992年6月，同时获得该地区的单道地震和宽角海底地震资料，主要集中在布莱克洋脊和卡罗来纳海隆，能清楚地观察到来自BSR的宽角反射偏移距（达6km）。为了了解区域性的变化和生成卡罗纳海隆高背景速度的二维平均速度模型，用宽角和垂直入射资料进行走时反演，然后做全波形反演业确定BSR的地震成因。最合适的模型显示了两处的BSR之下具相似的低速（1.4km/s），暗示圈闭了低饱和度（10％）的游离气，反演结果也显示有一薄层高速楱状体，最大速度为2.3km/s，刚好位于布莱克洋脊的BSR上方；计算了沉积物反射率，观察到卡罗来纳海隆具有较高的反射率，BSR之下的反射率增加几乎与两个站位的含气带对应。根据速度模型估算了水合物的浓度。另一方面，占沉积物总体积3%的水合物之平均浓度暗示布莱克洋脊地区水合物稳定带厚度少一半。卡罗来纳海隆水合物平均 浓度最大为20%，卡罗来纳海隆7%。这两处水合物浓度高，无法仅用原地生物活动来解释，可能与次生的聚集机制不关，因稳定域迁移引起水合物循环，可能影响两地的水合物凝聚。另外，流体向上排出的增加，也可以使 布莱克洋脊生存下去。     

An Experi mental Study on Wave-Induced Dynamic Stresses in Seabed

1 .IntroductionEvery year ,Taiwanis subjectedtotwo or three typhoonintrusions in average which always causedisasters . Most of the disasters which occur around the coastal zone are due to seabed instability andcoastal structure destruction caused bytyphoo…     

海洋局三所在河水痕量金属国际分析互校中名列前茅

为获得河水及其悬浮物样品中痕量金属浓度的可比性数据,评价参加相互校准实验室的分析水平,联合国教科文组织政府间海洋学委员会和联合国环境规划署下属的“方法、标准和相互校准专家组”于1986年组织了对泰国曼谷的河水及其悬浮物样品中痕量金属分析互校工作。参加这次互校的有美国、加拿大、日本、菲律宾、南朝鲜、泰国和中国共7个国家的8个实验室。我国国家海洋局第三海洋研究所黄自强和李锦霞两位副研究员领导的科研小组参加了这次相互校准。他们采用洁净分析技术,分析了河水样品中痕量溶解态铜、铅、锌、镉、钴、镍、铁和锰,所有分析结果均落在定值的一倍标准偏差范围内,名列前茅,获得较高评价,为我国争得了荣誉。这标志着该所河     

Oxidative stress in two populations of killifish (Fundulus heteroclitus) with differing contaminant exposure histories

A population of killifish (Fundulus heteroclitus) inhabiting a creosote-polluted inlet of the Elizabeth River demonstrates tolerance to the acute toxic effects exerted by contaminated sediments on reference site killifish. Previous data have suggested that upregulated antioxidant defenses contribute to short-term tolerance in killifish exposed to Elizabeth River sediments. This study investigated population differences in antioxidant defenses from wild caught Elizabeth River and reference population killifish in different seasons, and after being held in the laboratory. Parameters measured in the killifish were total glutathione concentrations (GSH(T)), activities of glutathione reductase (GR), glutathione peroxidase (GPx), and lipid peroxidation (LPO), all in adult hepatic tissues. The Elizabeth River population exhibited greater GSH(T), higher GPx activities, and increased LPO as compared to the reference population. Sex specific population differences were also observed in GSH(T) and GPx. Both populations displayed decreased GSH(T) and increased GR from early to late summer, as well as after being held in the laboratory. This study indicates that there are many factors that may contribute to differences in levels of antioxidant defenses in addition to exposure to contaminants, including reproductive status and environmental conditions.     

不同厚度冰层下的冰下火山喷发产物：两个来自南极的实例

不同厚度冰层下的冰下火山喷发产物：两个来自南极的实例Ｊ．Ｌ．Ｓｍｅｌｌｉｅ等本文着重介绍南极半岛两个保存最好的冰下层序（亚历山大岛的芒特皮纳佛和格雷厄姆地北部的布朗布拉夫）．通过对岩相和岩相组合的分析确定喷发时和喷发后作用过程，以及原始冰层的最小厚度...     

China's population: an alternative perspective

The author presents a selection of cartograms designed to illustrate aspects of the demography of China. Topics covered include population growth, density, regional variations in fertility, and age distribution. A discussion of the advantages of using cartograms (maps drawn proportional to a given variable) as opposed to conventional, area-based maps, is included.     

Far beyond the Gulf: the implications of warfare for Asian labour migration

The implications of the Gulf War are assessed for the countries in Asia that send labor migrants to the Middle East. "This paper seeks to examine the effects of...the loss of remittances (and related issues, including return migration), primarily in terms of the long-term implications of the War for the future of contract labour migration in the Asian region...."     

基于本体的地理信息服务查询组件设计

介绍了一种基于本体的服务发现组件设计方法,将基于本体的元数据和基于本体的查询结合起来,提高了基于OGC标准的网络地理服务发现的查询效率和准确性.     

制图综合中移位算法概述分析

本文首先对移位算法的发展史进行简要介绍,然后,在其基础上,根据各移位算法的思想特征,对各移位算法进行归纳,将其划分为七类,并对每一类算法的核心思想进行详细论述,最后,对各类移位算法进行评价,分析其优缺点,总结各类算法中的可借鉴思想,为更好地实现移位奠定基础。