Evaporative enrichment of oxygen-18 and deuterium in lake waters on the Tibetan Plateau

Stable isotopes (δ¹⁸O and δD) are useful tracers for investigating hydrologic and climatic variability on a variety of temporal and spatial scales. Since the early isotopic studies on mountainous glaciers in the late 1960s, a great deal of information has been generated on the isotopic composition of rainfall, snow, ice, surface waters, and lake carbonate sediments across the Tibetan Plateau. However, measurements of δ¹⁸O and δD values of lake water are scarce. Here we present a new dataset of δ¹⁸O and δD values of lake waters collected from 27 lakes across the plateau during a reconnaissance survey in summer 2009. δ¹⁸O and δD values of lake water range from −19.9 to 6.6‰ and from −153 to −16‰, respectively. The average values of δ¹⁸O and δD are −6.4 and −72‰, considerably greater than those of precipitation observed in this region. The derived Tibetan lake water line, δD = 5.2δ¹⁸O − 38.9, is significantly different from the global meteoric water line. Most of the lakes, including some freshwater lakes, contain water with negative values of d-excess (d). There is a negative correlation between d and total dissolved solids (TDS). Each of these findings indicates that evaporation-induced isotopic enrichment prevails in Tibetan lakes. Moreover, we develop an isotope modeling scheme to calculate E/P ratios for Tibetan lakes, using a combination of existing isotopic fractionation equations and the Rayleigh distillation model. We use the intersection of the local evaporation line and GMWL as a first approximation of δ¹⁸O and δD values of lake water inputs to infer an E/P ratio for each lake. Our modeling calculations reveal that although variable from lake to lake, the water budget across the plateau is positive, with an average E/P of 0.52. This is in good agreement with other observational and model data that show varying degrees of increases in lake size from satellite imagery and significant decreases in lake salinity in many lakes on the plateau over the last several decades. Together with the new isotopic dataset, the proposed modeling framework can be used to examine and quantify past changes in a lake’s hydrologic balance from the isotopic record of downcore carbonate sediments in the region.     

干旱区湿地信息的指数提取方法

以和田绿洲湿地为研究靶区,针对干旱区特有的地貌、气候特点,利用热红外波段在解译水体、湿地信息方面具有独特的优势,提出了基于热红外特征的干旱区湿地指数AZWI( Arid Zone Wetlands Index),详细叙述了AZWI的计算方法及过程,在总结传统主流方法的基础上,分别采用非监督分类、监督分类、决策树法和AZ...     

干旱区典型绿洲地表温度与植被覆盖度相关性研究

 绿洲空间热环境的研究是深入了解绿洲-沙漠间,以及绿洲内部物质能量流动机理的重要手段。利用TM/ETM+遥感影像反演了于田地区地表温度以及植被覆盖度,在统计地表温度-植被覆盖度二维散点图的基础上,研究不同结构区域下绿洲地表温度与植被覆盖度的相关关系。结果表明:①于田地区地表温度与植被覆盖度呈显著负相关关系,相关系数在-0.79158和-0.48816范围之间。②从1991年到2002年,于田绿洲内部区域地表温度与植被覆盖度散点图上各点分布由密集到分散,表明原有相对整体的植被覆盖地块被打散,成为多种土地类型交错的破碎化地块。③外部荒漠带及绿洲与荒漠交错带区域地表温度与植被覆盖度散点图上各点分布由分散到集中,表明绿洲外部荒漠化程度的逐年加剧,导致了绿洲外围植被覆盖有所降低,植被物种单一,植被多样性也呈现下降趋势。     

辽宁省沿海旅游整体发展战略研究——基于SWOT分析法

基于SWOT分析法对辽宁省沿海旅游整体发展进行定性和定量相结合的分析,结果表明内部因素得分0.65,外部因素得分0.74,处于坐标轴的东北方向。辽宁省沿海地区应充分发挥自身优势,克服劣势,避开威胁,把握发展机遇,实施整体发展五大战略:区域合作战略、商务休闲战略、优势战略、精品旅游路线战略和特色品牌战略。     

浙江省入境旅游发展的空间非均衡性研究与启示

浙江省入境旅游发展势头强劲,但省内各地市间入境旅游发展却参差不齐,非均衡性空间特征显著。通过分析浙江省11个地市1999—2008年共10年的入境旅游外汇收入指标,引入标准差、相对发展率和波士顿矩阵等分析方法,归纳浙江省入境旅游发展空间非均衡基本特征,同时,对影响非均衡产生的经济社会条件、区位条件、资源环境等因子的变化趋势进行深入探究,提出浙江省入境旅游可以由非均衡发展逐步向均衡化方向发展的观点。最后,从浙江省资源整合、区域联动角度,提出了浙江省入境旅游均衡化发展的对策思路。     

滠水河流域经济环境协调发展系统动力学模拟

从系统分析的视角出发,根据滠水河流域的自然与社会经济特点,构建经济环境协调发展系统动力学模型,模型主要参数包括人口、GDP、城市化水平、产业结构、水资源可利用量、水环境容量等。通过模型正负反馈环进行因果关系分析,考虑人口、资源、环境与经济之间的互动与制约关系,进行子系统划分,并确定人口平均增长率、服务业废水率、工业废水率以及水土流失率为敏感性因素,以敏感因素为核心,设计3种不同情景,得出经济、环境协调发展情景为最优方案。通过对不同发展情景的分析与比较,提出滠水河流域有必要采取措施控制人口增长,促进经济发展,保护生态环境,实现该流域经济与环境协调发展。     

风险管理视角下鄱阳湖流域暴雨洪涝灾害防御对策与建议

分析了鄱阳湖流域暴雨洪涝灾害分布情况,指出暴雨洪涝灾害防御在组织体系、部门联动、风险区划、防御规划、人员队伍、预警发布、灾防意识等方面存在的不足,最后提出了开展风险评估、制定防御规划、修订应急预案、健全法规体系、落实工程措施、完善组织体系、建立专业队伍、加强预警发布、构建联动机制、做好风险转移、开展科普宣传等针对性的改进措施和建议。     

湘东锡田A型花岗岩的年代学、Hf同位素、地球化学特征及其地质意义

对湘东锡田岩体进行的LA-ICP-MS定年结果表明,2个第一期中(细)粒斑状黑云母二长花岗岩样品的年龄分别为(220.9±0.6) Ma及(220.7±0.7)Ma;第二期中细粒二云母二长花岗岩的年龄为(154.4±0.7)Ma.两期花岗岩均为高钾、富碱、弱过铝质岩石.稀土元素总量较高,富集U、Th,亏损Ti、P等高场强元素和Ba、Sr等大离子亲石元素,具高的104 Ga/Al,显示A型花岗岩特征.印支期花岗岩略富集轻稀土元素,Eu异常较弱;燕山期花岗岩轻、重稀土元素分异不明显,Eu异常显著.Hf同位素研究显示,两期次花岗岩均具有较低的εHf(t)(-4.91～-11.04),亏损地幔二阶段模式年龄集中在1.6～1.8 Ga,与华夏地块古老的变质基底年龄一致.因此,锡田岩体是华夏地块古元古代地壳物质在伸展的构造背景下部分熔融的产物.锡田A型花岗岩复式岩体的确定,对于研究湖南东部在中生代印支、燕山两期构造事件中所处的构造背景具有重要意义,同时也为华南地区存在印支期A型花岗岩钨锡成矿作用增加了证据.     

The Stokes phase portraits of descattered pulse profiles of a few pulsars

The observing signals from pulsar are always influenced by the interstellar medium (ISM) scattering. In the lower frequency observation, the intensity profiles are broadened and the plane of polarization angle (PPA) curves are flattened by the scattering effect of the ISM. So before we analyze the scattered signal, we should take a proper approach to clear scattering effect from it. Observing data and simulation have shown that the Stokes phase portraits I–U, I–Q and Q–U are also distorted by the ISM scattering. In this paper, a simulation is held to demonstrate a scattering and a descattering of the Stokes phase portraits of a single pulse profile of a pulsar. As a realization of the simulation method, this paper has studied the descattering of Stokes phase portraits of lower frequency observation of PSR B1356?60, PSR B1831?03, PSR B1859+03, PSR B1946+35.     

基于构造解析重建的四川呷村银多金属矿床模型

四川省白玉县呷村银多金属矿床是中国著名的VHMS矿床之一,前人曾进行过详细的矿床模型研究。对于矿床下部脉状矿体大致呈层状平行于上部块状矿体的地质现象,前人曾提出"层状矿席+层控网脉状矿带"等模式。文章通过对呷村矿床地质特征的详细研究后认为,呷村矿床在印支期形成之后,遭受到燕山期弧-陆碰撞造山的强烈改造,导致矿区地层直立并倒转,并在能干性弱的流纹质火山岩中普遍发生层内韧性剪切变形,使原先近于垂直层状矿体和喷气沉积岩的下-中部脉状-网脉状矿体被构造置换为紧闭褶皱状、无根褶皱状、透镜体状,并近于平行于上部层状矿体。构造恢复表明,下-中部脉状-网脉状矿体原始三维形态为不整合的筒状或漏斗状,与上部层状矿体组成典型的"下筒上层"的"双层结构"。根据脉状-网脉状矿体和层状矿体的空间展布特征,在构造恢复的基础上重新建立了呷村VHMS矿床的双通道夹卤水池的矿床模型。该模型对矿区外围找矿有一定的指导意义。