定西地区1995-2000年间土壤侵蚀的变化与治理对策

严重的土壤侵蚀是定西地区生态环境恶化的主要原因,也是社会经济发展的主要限制性因素之一。利用数字遥感影像人机交互解译技术对1995年和2000年的土壤侵蚀进行调查,结果显示5 a来定西地区土壤侵蚀面积减少1 446.39 km²,减少了7.36%。其中轻度侵蚀减少5.63%,中度减少1.4%,强度减少0.03%,极强度减少0.30%。侵蚀程度整体上有所减轻,表明水土保持工作取得了一定成效。但土壤侵蚀面积仍然占土地总面积的80%以上,而且强度和极强度侵蚀面积减少不明显,土壤侵蚀仍然十分严重,水土保持的任务还相当艰巨。积极开展水土保持是定西地区实现山川秀美、脱贫致富和可持续发展的根本途径。     

2013年南沙群岛海域温跃层的季节变化及形成机理

利用调查数据及遥感数据揭示了2013年南沙群岛海域温跃层的季节变化特征,温跃层上界深度平均值春、夏、冬季基本一致,介于45~47 m之间,秋季最大,达60 m;温跃层厚度平均值夏、秋、冬季基本一致,介于85~87 m之间,春季相对较小,为78 m。温跃层强度平均值春、夏、秋、冬季几乎一致,介于0.13~0.15℃/m之间。调查海域温跃层上界深度季节变化的形成机理为:春季西深东浅的原因是西部受净热通量较小、大风速、负的风应力旋度以及中南半岛东部外海的中尺度暖涡和反气旋环流共同作用,东部近岸海域净热通量高值、风速相对较小及风应力旋度引起的Ekman抽吸效应共同控制;夏季深度分布较均匀的原因是10°N以北风致涡动混合强但受Ekman抽吸影响,10°N以南风致涡动混合弱但风应力旋度为负值;秋季深度较其他季节平均加深15 m的原因是南沙群岛海域被暖涡占据,暖涡引起的反气旋式环流使得温跃层上界深度被海水辐聚下压;冬季正的风应力旋度产生的Ekman抽吸和冷涡引起的气旋式环流共同作用,使得温跃层上界深度较秋季平均抬升15 m。     

南沙海洋沉积物中生物标志化合物的组成及地化意义

对１９９０年取自南沙海域１０２站位岩芯柱样中饱和烃进行色谱－质谱分析，研究沉积物中生物标志化合物组成和地球化学意义，结果表明，正构烷烃，类异戊二烯烷烃，甾烷和藿烷组成特征指示了其先质主要为海洋浮游生物和细菌，部分为陆源高等植物，反映了南沙海洋沉积有机质起源于这些生物，较丰富的胡萝卜烷在和Ｐｒ／Ｐｈ比值低，说明沉积环境具强还原性，随沉积物理埋藏深度增加，藿烷和藿烷以及藿烷异体之间，均存在明显的成岩转     

南沙群岛海区晚第四纪深海碳酸盐沉积作用

根据５个柱样分析，讨论了冰期一间冰期碳酸盐沉积作用变化，南沙海区碳酸盐旋回在３５００ｍ以浅表现为大西洋旋回，源于冰期陆源碎屑物质的稀释作用，相反，在３５００ｍ以下出现太平洋碳酸钙旋回，文中根据浮游有孔虫的溶解指数和种属数量讨论了冰期－间冰期溶解作用变化。     

南沙珊瑚礁生态系的碳循环

99-4航次对南沙珊瑚礁区进行了考察，利用现场投放沉积物捕捉器采集沉降颗粒物样品，从生物与非生物体系两个侧面对南沙珊瑚礁生态系的碳循环作了深入的研究。结果表明，无机碳是珊瑚礁生态系中各种样品碳的主要存在形式，总碳的收支主要受到溶解平衡与钙化作用的控制。有机碳在珊瑚礁泻湖中具有很高的循环效率，泻湖中垂直转移的颗粒有机碳有93％以上在进入沉积物之前被释放，其中生物碎屑的颗粒有机碳释放率约为99％。珊瑚礁植物尤其是与珊瑚共生的虫黄藻等的光合作用以及珊瑚礁的拟流网模型、休渔模型分别代表了构成珊瑚礁有机碳循环的两个主要方面，即：高效循环和稳定补充。因而珊瑚礁保护应当重点保护珊瑚礁水环境和生物多样性资源。     

The characteristics and significance of some lateglacial protalus ramparts in upland Britain

Arcuate and linear protalus ramparts of inferred Loch Lomond Stadial age are widespread in upland Britain outside the limits of contemporaneous glaciers. Survey and analysis of the morphology of nine ramparts suggests that these may have formed at the foot of slowly thickening snowbeds, with rockfall debris accumulating against their distal slopes, and that snowbed melting at the end of the stadial was uninterrupted by prolonged periods of stability or renewed growth. Rampart sediments consist of poorly-sorted assemblages of clasts with a variable infill of fines. Clast size and shape are strongly influenced by lithology, but rampart clasts are characteristically more angular and ‘slabbier’ than those of similar lithology in ice-marginal moraines. Ramparts may also be distinguished from moraines by their location, morphology, lack of a true matrix of fines and absence of erratics, and from talus-foot rock glaciers in terms of their width and the absence of flow structures. The mapped distribution of rampart altitudes across the Scottish Highlands displays a marked regional trend, with the lowest features in the west and south and highest in the Cairngorms. This pattern mirrors that of reconstructed firn line altitudes of Loch Lomond Stadial glaciers, and is inferred to reflect a pronounced eastwards and northwards decline in snowfall during the stadial.     

Elementary study of physical properties on surface sediments in Nansha Islands sea area

Elementary studies on surface sediment physical properties (physical-mechanic property, engineering features, acoustic parameters) of the Nansha Islands sea area in the South China Sea reveal that the seabed sedimentary environments are important factors of controlling sediment physical properties and the relations between them affect one another. At the same time, the relative figures of sediment physical properties and some experienced relations are given, which are beneficial to the later research and further studies. Project of the Multidisciplinary Oceanographic Team of the Chinese Academy of Sciences to the Nansha Islands in the South China Sea.     

Space-time variations of the frequency-energy relation for mining-induced seismicity in the Ostrava-Karviná mining district

The values of parameters of the relation logN=a–b logE characterize in general the level of seismicity of individual regions. In the present paper, a detailed analysis ofb values of the frequency-energy distributions was carried out with the aid of a database of seismic events recorded by the seismological networks in the Ostrava-Karviná Coal Mine District (Czech Republic), using the least squares regression and maximum likelihood method, as well. The determination ofb value was performed for a relatively large number of regions investigated and for different time series of observations. Special attention has been paid to induced seismic events statistics for the vicinity of one of the coalfaces in the Lazy Mine. It could be generally stated that lowerb values correspond to a higher level of induced seismic activity, while the higher ones correspond to a low and a moderate seismic activity.     

南沙海域近海层大气湍流结构及输送特征研究

本文根据南沙群岛渚碧礁的一次大气湍流观测资料，分析研究南沙海域的湍流热通量输送、方差相似性、风速各分量谱、温度谱及各湍流通量协谱等大气湍流结构和输送特征，并与陆地下垫面上的结果作了比较，得到了一些有关南沙海域大气湍流输送及湍流结构的新认识。     

南沙群岛海域岛礁鱼类资源的开发现状和开发潜力

南沙群岛海域蕴藏着丰富的礁栖性鱼类资源,是我国珊瑚礁渔业的主要作业渔场.根据近年来的渔业生产数据对开发现状进行了评价,判断南沙群岛岛礁鱼类资源尚处于轻度开发状态.通过采用初级生产力方法估算,南沙群岛岛礁水域鱼类的年生产量不低于2.1t·km-2,以年生产量的50%估算,潜在渔获量不少于5.5万t.