A biodiversity evaluation framework for restoration of aquatic macrophyte communities in shallow lakes driven by hydrological process management

Macrophyte community diversity and composition respond to ecosystem conservation and local environmental factors. In this study, we developed a multidimensional diversity framework for macrophyte communities, including the taxonomic and functional alpha and beta diversity. We used the framework to explore the relationships among water level regimes and these diversity parameters in a case study of China's Baiyangdian Lake. Analysis of indicators of hydrologic alteration divided the water level from 1959 to 2019 into four regimes (dry, <6.42 m; low, 6.42–7.23 m; medium, 7.23–8.19 m; high, >8.19 m). Alpha and beta diversity were significantly higher in the medium regime than in the low and high regimes. Redundancy analysis indicated that the maximum water depth significantly affected taxonomic alpha diversity, and total nitrogen (TN) and chemical oxygen demand (COD) concentration significantly affected functional alpha diversity, respectively. Mantel tests showed that TN, Secchi depth (SD), and water depth in the high water level regime significantly increased the total beta diversity and turnover components. TN was the main factor that increased total taxonomic beta diversity. Water level regime mainly influenced interspecific relationships by changing the TN and COD concentration. The water level should be maintained between the medium and high water level regimes to promote restoration of the macrophyte community and improve ecosystem stability. The biodiversity evaluation framework would provide a deeper insight into the hydrological process management for restoration of aquatic macrophyte communities in shallow lakes.     

Rainfall intensity affects runoff responses in a semi-arid catchment

The source and hydrochemical makeup of a stream reflects the connectivity between rainfall, groundwater, the stream, and is reflected to water quantity and quality of the catchment. However, in a semi-arid, thick, loess covered catchment, temporal variation of stream source and event associated behaviours are lesser known. Thus, the isotopic and chemical hydrographs in a widely distributed, deep loess, semi-arid catchment of the northern Chinese Loess Plateau were characterized to determine the source and hydrochemical behaviours of the stream during intra-rainfall events. Rainfall and streamflow were sampled during six hydrologic events coupled with measurements of stream baseflow and groundwater. The deuterium isotope (²H), major ions (Cl⁻, SO₄²⁻, NO₃⁻, Ca²⁺, K⁺, Mg²⁺, and Na⁺) were evaluated in water samples obtained during rainfall events. Temporal variation of ²H and Cl⁻ measured in the groundwater and stream baseflow prior to rainfall was similar; however, the isotope compositions of the streamflow fluctuated significantly and responded quickly to rainfall events, likely due to an infiltration excess, overland dominated surface runoff during torrential rainfall events. Time source separation using ²H demonstrated greater than 72% on average, the stream composition was event water during torrential rainfall events, with the proportion increasing with rainfall intensity. Solutes concentrations in the stream had loglinear relationships with stream discharge, with an outling anomaly with an example of an intra-rainfall event on Oct. 24, 2015. Stream Cl⁻ behaved nonconservative during rainfall events, temporal variation of Cl⁻ indicated a flush and washout at the onset of small rainfall events, a dilution but still high concentration pattern in high discharge and old water dominated in regression flow period. This study indicates rainfall intensity affects runoff responses in a semi-arid catchment, and the stored water in the thick, loess covered areas was less connected with stream runoff. Solute transport may threaten water quality in the area, requiring further analysis of the performance of the eco-restoration project.     

在BPL信道上增加数据广播内容的探讨

分析了现有罗兰C（包括BPL）在授时方面存在的不足，提出了在BPL信道上实现数据广播的主要目的。详细讨论了各种可能的数据信息的结构，并给出了有关参数和数据的计算方式和公式。认为发播内容的选择是由期望的系统功能决定的，广播内容的编排则与具体实现技术相关。最后给出了在不同调制方法下的传输速率，这是合理编排广播内容的基础。     

First Post-Newtonian Angular Momentum In Relativistic Celestial Mechanics

With a new theory on the 1PN celestial mechanics recently developed by Damour, Soffel and Xu (1991,1992,1993,1994), definitions and expressions of the 1PN spin angular momentum are investigated and analysed. The total spin angular momentum of a system of extended bodies such as the solar system is calculated and expressed as the function of local parameters and observables under reasonable assumptions, which would find its application in the evolution and dynamics of systems of celestial bodies. This revised version was published online in July 2006 with corrections to the Cover Date.     

WIMPs and solar evolution code

The Saclay solar evolution code is used to check the effect of WIMPs on solar evolution. In this paper we study the effects of various types of Cosmion-matter interactions, give constraints on the crosssections compatible with the measured neutrino rate of 2 SNU on chlorine, and relate these constraints to ongoing dark matter detection experiments.Unité associée au CNRS UA 280, F-75251 Paris Cedex 05, France.On leave from LPC, Collège de France.     

1989年8月17日太阳射电尖峰事件的准周期脉动及EFB分析

本文分析了云南天文台１０ｍ射电望远镜在２ｌｃｍ波段上观测到的一次尖峰辐射事件，这次事件发生在５６２９活动区（Ｓ１６Ｗ１０９），它伴随了Ｘ２·９／ＳＦ耀斑及边缘耀斑环，并且有质子流量的上升和一次罕见的地磁场突然反相脉冲与之对应．我们从耀斑环的Ｈβ照片可以看出，在尖峰辐射发生前，原先存在的耀斑环的顶部开始变亮，而尖峰开始后环顶亮度达到极大，说明这次尖峰辐射与耀斑环顶部增亮有关，辐射很可能来自环顶．从尖峰事件的时间轮廓得到的ＦＦＴ功率谱表明存在１５０ｍｓ的准周期脉动．按照Ｍｃｌｅａｎ等人的模型，即脉动是由俘获在磁通管内的电子的径向振荡引起，可以推断，这次尖峰辐射与Ｆｅｒｍｉ机制激发快速电子有关，且尖峰的发生需要被俘获的电子．此外，我们将这次尖峰事件分解为几百个元耀斑爆发（ＥＦＢ），并且讨论了这些ＥＦＢ的性质．     

基于GPS实现测频等功能的虚拟仪器的研制

设计和研制了一种适用于大专院校示范教学实验的虚拟仪器。该虚拟仪器以GPS接收模块输出的1PPS(秒脉冲)信号为基准,测量无源石英晶体振荡器频率,同时利用GPS信号实现了仪器的时间同步与测距功能。从硬件和软件两方面描述了该虚拟仪器的构成及设计方法,主要介绍和讨论基于GPS和虚拟仪器技术实现多功能测量的途径。     

赣南淘锡坑钨多金属矿床花岗岩和云英岩岩石特征及云英岩中白云母40Ar/39Ar定年

赣南崇义县淘锡坑钨矿位于南岭东西向构造带东段,属于以黑钨矿石英脉型为主的钨多金属矿床。矿床形成与燕山期中酸性岩浆作用有密切关系,石英矿脉受一组北西向断裂控制,穿切新元古界。本文在淘锡坑钨矿区3个揭露到花岗岩体顶部的中段（206、106、56中段）采集到岩体顶部云英岩样品,利用40Ar/39Ar同位素定年测得云英岩中的白云母的坪年龄分别为152.7 ± 1.5 Ma（206中段）,153.4 ± 1.3 Ma（106中段）,155.0 ± 1.4 Ma（56中段）。与前人用其他方法测定的花岗岩成岩和成矿年龄几乎一致。花岗岩和云英岩全岩稀土元素均具有M型四分组效应和强烈的Eu亏损特征,反映出花岗质岩浆经历了高度分异演化及其岩体结晶晚期流体/熔体相互作用。综合前人在南岭地区同类矿床的研究资料,可知南岭地区160～150Ma成岩成矿作用主要分布于南岭中-东段,可能为大陆边缘弧后岩石圈伸展的构造动力学背景的产物。     

阳宗海湖泊水质与来水量的关系研究

水资源的不合理开发利用改变了湖泊原有的来水条件,破坏了水环境与河流系统之间的平衡关系．认识不同时期流域来水条件下湖泊水质变化特点,研究两者之间的关系,对于探索有效的水环境改善措施,实现阳宗海湖泊可持续开发有着重要意义。本文利用阳宗海流域水文资料．采用水量平衡还原方法计算得到了阳宗海1985-2005年的入湖水量,并采用1985-2005年水质监测资料。分析了丰水期和枯水期两个不同时期湖泊水质与来水量之间的关系。得到枯季总磷、总氮与来水量呈负相关,丰水期与来水量呈正相关关系的结论。分析了不同来水条件下阳宗海湖泊水质变化的特点．对制定改善湖泊水环境的调度措施提供有益参考。