地下水循环结构的动力学研究进展

由地下水补给、径流和排泄过程构成的地下水循环运动,是水文循环的重要组成部分,也是水文地质学的基本研究对象.地下水循环在空间上表现为不同结构单元的组合,存在以含水层特性为依据的介质结构和以渗流场为依据的动力结构2种划分方法.地下水流系统是动力结构意义上的地下水循环单元.近10年来,区域地下水流系统理论取得了显著进展,更加全面深入地揭示了地下水循环结构的动力学特性.通过对河间地块地下水流系统的研究,发现潜水面最高点并非地下水分水岭的准确位置.在盆地尺度上,系统研究了沟谷地貌、降水入渗强度、渗透性随埋深变化和盆地厚度等因素对潜水面波形与地下水循环动力结构的影响,初步发现了动力结构的周期性或趋势性演化特征.通过大规模流线路径的精细识别或驻留时间的统计分析,提出了三维地下水循环单元的划分方法.在水文地质效应方面,发现地下水循环的动力结构对地下水年龄的分布有重要影响.地下水循环的动力结构反映了不同补给区和排泄区之间的水力联系,在盆地尺度地球化学过程、流域尺度生态水文过程中发挥着关键作用,未来的研究重点是三维地下水循环的动力特性和演变规律.     

UCODE反演程序的原理及应用

对地下水模型进行反演是模拟过程中的一个必要步骤,使用反演程序自动校正模型可快速确定最佳拟合的参数值,分析参数对模拟结果的敏感性,比人工试算-调整法更为优越。UCODE是一款被广泛应用的地下水模型反演程序,它使用高斯牛顿法进行参数优化,反演结果对参数初值有一定的依赖性。通过建立假想的非稳定流模型,进行6组数值试验,验证了UCODE程序的实用性。尽管参数的初始取值会影响反演的进程,但只要取值适当,UCODE就能实现优化参数的目的。     

川06井水位固体潮效应变化初探

通过分析承压井孔储水效应对井水位固体潮效应(井潮)的影响, 重点研究了含水层储水系数S和导水系数T对潮汐排水响应的影响, 以探讨井潮变化形成的初步原因. 以川06井为例, 通过对实测井孔水位数据进行潮汐分析, 得到井孔储水效应引起的相对振幅A和相位移η, 进而分析A和η随时间变化的规律以及两者之间的关系. 结果表明, 井潮变化主要受井孔储水效应变化影响; 在潮汐排水响应阶段, 井潮主要受含水层导水系数T(或渗透系数K)影响, 而受储水系数S影响较小.     

Discovery of a Late Permian Angara-Cathaysia mixed flora from Acheng of Heilongjiang,China, with discussions on the closure of the Paleoasian Ocean

This work documents a new flora from the Upper Permian Hongshan Formation of Acheng County, Heilongjiang Province, Northwest China. The flora consists of 20 species: Paracalamites sp., Pecopteris tangwangheensis Huang, Callipteris obese Huang, Callipteris shenshuensis Huang, C. tangwangheensis Huang, C. heilongjiangensis Huang, C. zeilleri Zalessky, C. sp., Comia yichunensis Huang, C. tenueaxis Huang, Iniopteris sibirica Zalessky, Supaia teiliensis Huang, Compsopteris tchirkovae Zalessky, C. cf. adzvensis Zalessky, Nilssonia sp. 1, Nil. sp. 2, Taeniopteris cf. densissima Halle, T. cf. nystraemii Halle, T. sp. and Noeggerathiopsis derzavinii Neub. It is dominated by Angara species but mixed with some typical Cathaysian elements. The age of the flora is assigned to late of the Late Permian according to the stratigraphic ranges of the known species and the comparisons of it with the similar floras. The new discovery indicates that the final collision between the North China Plate and Siberian Plate occurred in Late Permian along the Xar Moron River-Changchun-Yanji sutured zone, and the Paleoasian Ocean was finally closed at the end of the Permian.     

白垩纪中期海相富有机碳沉积的地球生物学背景

白垩纪中期(约125～88Ma)海相富有机碳沉积广泛发育于全球各主要洋盆和沉降区,是许多大油田的重要烃源岩。文中从地球生物学的角度探讨了当时海相富有机碳沉积的地质背景和主控因素,认为在白垩纪中期全球事件频发的特殊背景下,保存条件(大洋缺氧)和生产力的提高共同控制了有机质的富集。大洋缺氧不但加快了海洋生物的灭绝和更替,使有机质大量堆积,而且促进了营养元素(P、N、Fe等)的再生和厌氧自养型海洋微生物(如蓝细菌、绿硫细菌和古菌类等)的极度繁盛,提高了生产力水平;而高的生产力又反过来加剧了海洋的缺氧。新的研究成果(Os同位素证据)表明,白垩纪大规模海底火山作用引发了持续的温室效应和海水循环的静滞、紊乱以及弱上升流发育,进而导致生产力的提高和大洋缺氧事件(OAE)的发生,最终造成有机质的广泛堆积和保存。     

Evaluating conservation effectiveness of nature reserves established for surrogate species: Case of a giant panda nature reserve in Qinling Mountains, China

Many nature reserves are established to protect the habitat needs of particular endangered species of interest but their effec-tiveness for protecting other species is questionable.In this study,this effectiveness was evaluated in a nature reserve network located in the Qinling Mountains,Shaanxi Province,China.The network of reserves was established mainly for the conservation of the giant panda,a species considered as a surrogate for the conservation of many other endangered species in the region.The habitat suitability of nine protected species,including the giant panda,was modeled by using Maximum Entropy（MAXENT） and their spatial congruence was analyzed.Habitat suitability of these species was also overlapped with nature reserve boundaries and their management zones（i.e.,core,buffer and experimental zones）.Results show that in general the habitat of the giant panda constitutes a reasonable surrogate of the habitat of other protected species,and giant panda reserves protect a relatively high proportion of the habitat of other protected species.Therefore,giant panda habitat conservation also allows the conservation of the habitat of other protected species in the region.However,a large area of suitable habitat was excluded from the nature reserve network.In addition,four species exhibited a low proportion of highly suitable habitat inside the core zones of nature reserves.It suggests that a high proportion of suitable habitat of protected species not targeted for conservation is located in the experimental and buffer zones,thus,is being affected by human activities.To increase their conservation effectiveness,nature reserves and their management zones need to be re-examined in order to include suitable habitat of more endangered species.The procedures described in this study can be easily implemented for the conservation of many endangered species not only in China but in many other parts of the world.     

中国沿海围网技术参数的分析和比较

本文对中国沿海几十种围网的技术参数进行了分析和比较。     

日本盘鲍×皱纹盘鲍子代杂种优势的RAPD分析

本文通过对日本盘鲍 (D)、皱纹盘鲍 (H)及其二者的正反杂交子代 D♀× H♂ (DH)、D♂× H♀ (HD)四样本的基因组 DNA进行 RAPD标记分析。探讨了杂种优势产生的分子遗传机制。从 4 0个随机引物 (OPK,OPV系列 )中筛选出 12个引物进行扩增 ,共得到 113条清晰稳定的扩增带 ,多态率占 4 3.3%。其中四群体各有其特异扩增位点。另外 D与 DH,H与 HD及 D与 DH,HD等间亦存在共享片段。四群体内相似性指数各自为 0 .798(H)、0 .799(D)、0 .777(HD)、0 .788(DH)。可见正反杂交子代群体内相似性指数皆低于两亲本 ,这表明杂种子代基因组发生的变异更大些。皱纹盘鲍与其正反杂交子代的相对遗传距离分别为 0 .0 76 ,0 .0 95,而日本盘鲍与其正反杂交子代的相对遗传距离分别为 0 .0 31,0 .0 33,前者明显大于后者 ,这表明杂交子代与两亲本的遗传距离不是对等的 ,而是更偏向日本盘鲍。     

Improved prediction of the threshold of surf-riding of a ship in steep following seas

An extended version of Melnikov's method is implemented in order to predict more accurately the threshold of global surf-riding for a ship operating in steep following seas. The key advantage of the proposed method is that it overcomes the limitation of small damping and/or small forcing that are intrinsic to the implementation of the standard Melnikov's method. A reference ITTC ship is used here by way of example and the result is compared to that obtained from standard analysis as well as numerical simulations. Because of the primary drawback of the extended Melnikov's method is the inability to arrive at a closed form equation, in this work the authors arrive at a “best fit” approximation to the extended Melnikov numerically predicted result.     

Interaction between waves and an array of floating porous circular cylinders

The present study theoretically as well as experimentally investigates the interaction between waves and an array of porous circular cylinders with or without an inner porous plate based on the linear wave theory.To design more effective floating breakwaters,the transmission rate of waves propagating through the array is evaluated.Each cylinder in the array is partly made of porous materials.Specifically,it possesses a porous sidewall and an impermeable bottom.In addition,an inner porous plate is horizontally fixed inside the cylinders.It dissipates the wave more effectively and eliminates the sloshing phenomenon.The approach suggested by Kagemoto and Yue(1986) is adopted to solve the multiple-scatter problem,while a hierarchical interaction theory is adopted to deal with hydrodynamic interactions among a great number of bodies,which efficiently saves computation time.Meanwhile,a series of model tests with an array of porous cylinders is performed in a wave basin to validate the theoretical work and the calculated results.The draft of the cylinders,the location of the inner porous plate,and the spacing between adjacent cylinders are also adjusted to investigate their effects on wave dissipation.