海南岛东南部新村港和黎安港潮汐特征及潮汐汊道P-A关系

以2013年8月实测的水位和流速资料为依据, 基于调和分析和统计方法分析了海南岛东南部新村港和黎安港潟湖的潮汐和潮流特征及其分布规律, 并探讨了潮汐汊道的P-A关系及其影响因素。结果表明, 双湖附近海域潮汐以全日分潮O1和K1为主, 半日分潮M2次之, 浅水分潮亦较显著, 属于非正规的全日混合潮; 调和常数反演的潮位与实测潮位基本吻合, 表明潟湖水位主要受潮汐控制。此外, 双湖均存在潮高日不等和涨落潮历时不等的现象, 涨潮历时略大于落潮历时。新村港平均高潮位0.65m, 较黎安港高0.15m; 平均低潮位-0.28m, 较黎安港低0.06m。新村港平均潮差0.50m, 最大可能潮差1.63m; 黎安港平均潮差0.36m, 最大可能潮差1.22m; 双湖平均潮差相差0.14m, 而最大可能潮差相差较大, 约0.41m。新村港平均潮差由口门向湾内有增大的趋势, 而黎安港却恰好相反。实测和模拟结果显示新村港和黎安港潟湖潮流分布格局类似, 都呈现出口门流速较大, 潟湖内部区域流速较小(小于0.1m/s)的分布规律, 且落潮流略强于涨潮流。新村港和黎安港的P-A值与华南海岸潮汐汊道P-A关系回归线吻合较好, 其中黎安港P-A值基本在华南海岸P-A关系回归线上, 而新村港略微有点偏离, 这说明新村港和黎安港潮汐汊道基本处于均衡状态。     

Spatial Disparity of Slope Farmland and Food Security in Three Gorges Area

As an important measure of ecoenvironmental construction, the process of de-farming in slope farmland is being undertaken gradually in the whole China. Meanwhile, the problem of reducing in food yield in de-farming areas can not be neglected any more. It is especially the case in areas with concentrated slope farmland and inconvenient transportation. In this paper, we analyze the causes of hidden troubles in food security, and the spatial relationship between farmland and slope farmland in the reservoir area of Three Gorges, and unveil the spatial disparity of contradictions between food supply and demand. Finally, combining the accessibility of areas, three different spatial types of food security, food security area, food alert area, and food crisis area, are divided.     

Paleomagnetic Excursions Recorded in the Yanchi Playa in Middle Hexi Corridor, NW China Since the Last Interglacial

Paleomagnetic determinations on lithologieal profiles of two paralleled long drillin gcores covering the past 130 kyr B.P., GT40 and GT60,from the Yanchi Playa in the arid Northwestern China indicate that a series of pronounced paleomagnetic excursions have been documented. By correlating our results with published regional and worldwide reports 4 excursion events out of 10 apparent reversal signals (labeled from GT-1 to GT-10) were identified as excursion events coeval with the Mono Lake Event (28.4 kyr-25.8 kyr), Laschamp Event (43.3 kyr-40.5kyr), Gaotai Event (82.8 kyr-72.4 kyr) and the Blake Event (127.4 kyr-113.3 kyr), respectively. GT-9 correlates with the above-mentioned Gaotai Event,GT-7 and GT-6 correspond to two stages of the Laschamp Event and GT-5 to the Mono Lake Event. It is noteworthy that the so-called Gaotai Event has not been reported as a pronounced paleomagnetic excursion in the Northwestern China. Every magnetic excursion event corresponds to paleointensity minima, anteceding those established abrupt paleoclimatic change events, such as the Younger Drays and the Heinrich Events (H1-H6). Here, we tentatively propose that these geomagnetic excursions/reversals can be viewed as precursors to climate abruptness. During the transitional stages when the earth‘s magnetic field shifted between a temporal normal and a negative period, the earth‘s magnetic paleointensity fell correspondingly to a pair of minima. Although more precise chronology and more convincing rock magnetic parameter determinations are essentially required for further interpretation of their intricate coupling mechanism, these results may have revealed, to some extent, that the earth‘s incessantly changing magnetic field exerts an strong influence on the onset of saw-tooth shaped abrupt climate oscillations through certain feedback chains in arid Central Asia or even North Hemispheric high latitude regions.     

北固山淡水潮汐湿地土壤对铜(Ⅱ)和铬(Ⅵ)的吸附特征研究

以长江河口地区北固山淡水潮汐湿地为研究对象,采用一次平衡法研究了生长有芦苇(Phragmites austra-lis)、虉草(Phalaris armdinacea)植物的湿地土壤和边滩裸地对重金属Cu(Ⅱ)和Cr(Ⅵ)的吸附特征。结果表明,湿地土壤对Cu(Ⅱ)的吸附受到植物类型与温度变化效应的交互影响。20℃时,生长有芦苇的湿地土壤对Cu(Ⅱ)的吸附量最大,生长有虉草的湿地土壤次之,边滩裸地最小;当温度的升高至30℃时,上述差异明显减小。对以阴离子形式存在的Cr(Ⅵ)而言,湿地土壤和边滩裸地对其吸附量的植物类型差异性不明显。当温度从20℃升高至30℃时,湿地土壤和边滩裸地对Cu(Ⅱ)、Cr(Ⅵ)的吸附量都减小,反映出研究区湿地土壤对两种重金属的吸附机制表现为化学吸附作用较弱,物理吸附作用相对较强,吸附呈放热过程。Freundlich方程是描述淡水潮汐湿地土壤Cu(Ⅱ)、Cr(Ⅵ)等温吸附的最佳模型,方程中常数n和k的大小能够体现吸附过程中存在的植物类型与温度变化影响效应,比较真实的反映了吸附的过程。     

迟缓爱德华氏菌致病相关因子的研究进展

迟缓爱德华氏菌(Edwardsiealla tarda)是引起多种鱼类产生爱德华氏菌病(edwardsiellosis)的病原菌。随着水产养殖业的日益发展,致病性迟缓爱德华氏菌对水产养殖业的危害也越来越严重。有关迟缓爱德华氏菌的致病机理至今还没有系统、清晰的阐释,但近些年对其致病相关因子的研究已逐渐深入。文中对迟缓爱德华氏菌的生物分型、快速检测技术等进行了简要阐述,并对该病原菌的主要致病相关因子,包括黏附因子、抵抗宿主免疫机制的酶类、各种毒素、Ⅲ型和Ⅵ型分泌系统、载铁体及磷酸盐特异转运操纵子进行了详细阐述,以期为迟缓爱德华氏菌致病机理的进一步深入研究及其防治提供参考和借鉴。     

全球GNSS掩星计划进展

主要介绍了国际上GNSS掩星计划（包括GPS／MET、Orsted、Sunsat、SAC-C、CHAMP、GRACE、FedSat、COSMIC、METOP和ACE＋计划）发展现状、科学任务及系统组成、取得的进展以及未来的发展趋势。通过总结指出,自GPS／MET计划实施后,掩星探测技术逐步完善并向业务化运用迈出了一大步;今后GNSS掩星探测将向多星探测和混合探测方向发展,国际化合作成为项目的开发和研制趋势     

威连滩冲沟砂黄土的风蚀与降雨侵蚀模拟实验

 通过风洞与模拟降雨实验，研究了风力与降雨对青海省贵南县威连滩冲沟砂黄土的复合侵蚀作用。实验得出：①风蚀后的降雨使砂黄土表面在风干过程中形成了一层较为坚硬的结壳，增大了土壤的抗蚀性，降低了第二次风洞实验后期的风蚀率;②土壤水分与人为扰动是影响土壤风蚀的两个重要因素。当土壤水分较小时，风蚀率受人为扰动影响巨大;当土壤水分较大时，人为扰动对土壤风蚀的影响较小;③在持续降雨的实验条件下，砂黄土的产流、产沙量随着雨强的变化而改变。这种变化与表土的侵蚀率、可蚀性物质的多少、土壤水分以及土壤的入渗率等都有很大的关系。     

一次强风暴的垂直环境特征数值模拟分析

应用MM 5模式对东北冷涡诱发的 2 0 0 2年 7月 1 2日强风暴进行了数值模拟 ,较成功地模拟出中尺度强对流风暴。发现冷涡后部中层干冷空气绝热下沉是东北冷涡 70 0hPa附近干暖盖形成和维持的重要机制 ,而低层暖湿气流爬升及干暖盖的抑制作用是东北冷涡强对流不稳定能量积累的重要机制。风暴发生前持续的低层西南风到中层西北风的风垂直切变产生的差动平流 ,加剧了层结不稳定 ,而风暴临近风垂直切变方向的快速逆转使热成风不平衡 ,必须通过激发垂直环流以适应其变化 ,对风暴发展有重要作用。