The fronts of the Huanghai cold water mass (HCWM) induced by tidal mixing

Since Simpson and Hunter proposed in 1971 the idea that shallow water fronts were induced by tidal mixing, many authors have investigated the tide induced shallow water fronts in various areas. It was generally assumed that a critical value of the stratified parameterK=log₁₀(H/U ³) may be used to identify the location of these fronts. Here, H means the depth of sea waler. U denotes the characteristic velocity of tidal current. and the critical value ofK is generally laken as 1.8–2.0. In this paper. Simpson-Hunter’s stratified parameterK was calculated by using quasi-maximum current velocity (which consists of the six main tidal constituents. i.e.M ₂.S ₂,O ₁.K ₁.M ₄,MS₄) in the H ranghai Sea (Yellow Sea) and in the northern Donghai Sea (East China Sea) as well. Caleulated results show that the areas of the Subei (the northern part of Jiangsu) Shoal. the area off the mouth area of the Changjiang (the Yangtze) River, along the coast of Shandong Peninsula. and along the western coast of Korea, the tidal mixing is strong. Calculations also show that along the whole boundary of the HCWM and also along the western boundary of the cyclonic eddy in the northern Donghai Sea, i.e. along the fronts, the value ofK is found to be very close to the eritical value 1.8. It is also to be noied that at these locations, the temperature of the surface water is very low. These clearly show that shallow water fronts in the Huanghai Sea and in the northern Donghai Sea as well, are induced by tidal mixing. Contribution No. 1241 from Institute of Oceanology, Academia Sinica. This paper was published in Chinese in theOcean. et Limn. Sinica 16(6): 451–459, 1985.     

The first extra-large helium-rich gas field identified in a tight sandstone of the Dongsheng Gas Field,Ordos Basin,China

Science China Earth Sciences - Helium gas is a scarce but important strategic resource, which is usually associated with natural gas. Presently, only one extra-large helium-rich gas field has been...     

Revealing storage-area relationship of open water in ungauged subalpine wetland — Napahai in Northwest Yunnan, China

Mountains and plateaus in Southwest China contain many subalpine and alpine wetlands, with significant hydroecological functions. But ungauged or poorly gauged conditions limit the study and understanding of hydrological regimes of these wetland types. This study selects an ungauged subalpine wetland-Napahai in Northwest Yunnan, China-as a case for developing a practical approach to revealing its storage-area relationship of open water. A Trimble R8 GNSS (Global Navigation Satellites Systems) RTK (Real-time Kinematic system) and sonar fathometer were used to survey fine-resolution elevation data and generate a digital elevation model of the Napahai Wetland. Forty-four Landsat images from 1987 to 2011 were collected, and the Normalized Difference Water Index was used to classify open water features in the area. The area of open water in Napahai was calculated for each phase. With these data and a developed conceptual model, the storage of open water for each phase was estimated using ArcGIS tools. Both storage and area of open water showed significant intra-annual and inter-annual variations. In the rainy season, the monthly change of average storage of open water in Napahai showed about 1-2 months lag behind mean monthly rainfall. The storage-area relationship of open water was well fit by a power function equation (R 2 ≈0.91, n=44). This study indicates that if detailedelevations are available for similarly ungauged subalpine wetlands in Southwest China, researchers can use this practical approach to estimate multi- temporal areas and storages and reveal the storage-area relationship of open water in the wetlands. The study provided valuable information of this case wetland for optimizing its hydro-ecological managements and a new method to wetland researchers and managers for the hydrological study of similarly ungauged wetland complex.     

试论灾变的进化意义

地球灾变一向被看成是生物进化的破坏性因素,但本文认为,正是这些灾变给生物进化带来一片生机。每一次灾变使旧有生物成批衰亡,往往有几十上百种生物一起灭绝,但同时也使新兴生物的崛起和繁盛有了广阔的生态空间。不仅如此,灾变还可以使旧生物跃变形成新生物,甚至可以制造、创造新生命。生命形成的一系列化合合成反应所需要的巨大能量,恰恰可能来源于形成灾变的火山作用、宇宙射线照射作用等。     

南海北部深水区荔湾凹陷构造演化及其石油地质意义

荔湾凹陷北与白云凹陷相邻,南与双峰盆地（南海西北次海盆）相接,发育于洋陆过渡边界,具有独特的结构构造特征。选取荔湾凹陷为研究对象,在3D地震资料解释的基础上,以断裂特征分析厘定凹陷性质、构造古地貌恢复解析凹陷结构,进而指出古地貌恢复和构造演化对油气勘探的影响。研究获得三方面的创新性认识：①荔湾凹陷为洋陆过渡壳上发育的断坳,断坳作用占主导地位;②32Ma的底辟作用将荔湾凹陷改造为“四洼三凸”的构造格局,恩平组沉积期凹陷北部是一个连通的洼陷;③恩平组沉积期连通洼陷的古地貌有利于三角洲（烃源岩）的发育,背斜型圈闭的定型受控于32Ma的底辟作用,是荔湾凹陷油气勘探的有利目标。     

南极普里兹湾附近海域表层海流特征分析

利用第29次南极科考期间在普里兹湾海区释放的8个Argos漂流浮标所获的总计662 d的数据,对普里兹湾及其邻近海域的表层海流特征进行了分析,并和以前的研究结果进行对比,结果表明:普里兹湾西部和北部表层海流基本呈现向西的流动,说明此地区的表层海流以沿南极大陆的逆时针沿岸流为主。普里兹湾东部海流呈现先向南再向西或先向南再向北的流动,普里兹湾西北部海流呈现向南的流动。8个浮标平均流速在0.02—0.20 m·s~(-1)之间,最大流速为1.57 m·s~(-1),流速1.0 m·s~(-1)的大流速区主要集中在普里兹湾、克洛斯角外侧、达恩利角外侧海域,流速1.5 m·s~(-1)的大流速区只出现在普里兹湾、克洛斯角外侧两处海域。     

潮汐形变资料中地震前兆信息的识别与提取

将小波变换的多分辨率分析引入潮汐形变资料处理中，对近年来云南地区的3次强震前的潮汐形变观测资料进行了处理与分析，发现在地震前2～5个月，震中附近的形变台站都接收到一个频段相同的异常信号，且它们之间是相关的，相关系数达80％以上，由此可以确定信号是由同一个源发出来的。出现在多个台站的相同频段的异常信号很可能就是我们想要得到的地震前兆信息。     

Total N,total P and organic matters content in floodplain soils of Xianghai Nature Reserve

Soil sediment samples of 10 layers with a spacing of 10 cm each were collected in different floodplain zones adjacent to Huolin River in the Xianghai Nature Reserve, and contents of total N, total P and organic matters were analyzed. The results showed that contents of total N, total P and organic matters were generally decreasing with the increase of distance from sample locations to the river channel, and contents of the three items were generally higher in the upper soil layer than that in the lower soil layer. The content variations displayed how flooding functions influenced nutrient matter content variations in floodplain soils since the flood inundation frequencies of the sample locations varied. The correlation analysis displayed that there were remarkable relativities between total N, total P and organic matters within definite spatial distance from the Huolin River channel.     

贵州省乡村贫困空间格局与形成机制分析

以贫困态势严峻、区域内部贫困差异大的贵州省为研究区,分析了贵州省区县层面乡村贫困的空间异质性和空间依赖性格局,定量测度了乡村贫困空间差异的影响因素和因素效应的空间差异性,进而归纳了贵州省乡村贫困的形成机制。结果发现,贵州省区县乡村贫困具有时空稳定性,呈现出东、南、西部高而中、北部低的“马蹄”形空间异质性格局。区县贫困存在较强的空间依赖性,“高-高”型贫困地域即空间贫困陷阱区域,集聚分布在贵州省的东南部、南部。定量模型发现,坡度、到所在市中心的距离、青少年人口占比、少数民族人口占比是导致贵州区县层面乡村贫困空间差异的显著因素,且这些因素的效应水平呈现出不同的空间模式。产业发展受限、劳动力流动性差、金融和人力资本积累不足是贵州贫困空间形成的主导机制。最后建议扶贫政策层面应将基于地方和基于人的政策相结合。