卤水资源开发利用技术述评(续完)

总结并讨论了国内外从卤水中提取钾、镁、锂、硼、溴等资源的分离提取技术,并对其技术的应用范围、优缺点及技术发展趋势进行了述评。     

南极长城站区土壤重金属含量特征及来源分析

频繁的人类活动对南极生态环境的影响越来越受到关注,在南极长城站周边人类活动密集区对土壤进行采样的基础上,分析长城站周边地区表层土壤中重金属含量特征,并结合近20年来长城站周边土壤中主要重金属含量的分布,展开对比研究,探讨长城站区主要重金属元素的来源。结果表明,8种主要重金属在长城站表层土壤中都有不同程度的富集,站区频繁的车辆活动使得汽车尾气排放及汽车轮胎磨损产生大量含重金属的有害气体和粉尘,这些物质沉降在站区土壤表层或许是南极长城站区土壤重金属富集的重要原因之一。     

Geochemical and isotopic evidence of a groundwater source in the Corral Canyon meadow complex,central Nevada,USA

Major inorganic ions and stable carbon and oxygen isotopes in stream water, groundwater, groundwater seeps and springs were measured in the Corral Canyon meadow complex and watershed in the Toquima Mountains of central Nevada, USA. The purpose of the study was to determine whether stream water or groundwater was the source of water that supports vegetation in the meadow complex. Water samples from the watershed and meadow complex were mixed cation–HCO₃ type. Stream water sampled at different locations in the meadow complex showed variations in temperature, pH and specific conductance. The cation–anion proportions for stream water were similar to groundwater, groundwater seeps and runoff from the meadow complex. Stable oxygen isotope ratios for stream water (?17·1 to ?17·6‰ versus VSMOW) and groundwater and groundwater seeps in the meadow site (?17·0 to ?17·7‰ versus VSMOW) were similar, and consistent with a local meteoric origin. Dissolved inorganic carbon (DIC) and the δ ¹³C_DIC for stream water (?12·1 to ?15·0‰ versus VPDB) were different from that of groundwater from the meadow complex (?15·3 to ?19·9‰ versus VPDB), suggesting different carbon evolution pathways. However, a simple model based on cation–δ ¹³C_DIC suggests that stream water was being recharged by shallow groundwater, groundwater seeps and runoff from the meadow complex. This leads to the conclusion that the source of water that supports vegetation in the meadow complex was primarily groundwater. The results of this study suggest that multiple chemical and stable carbon isotope tracers are useful in determining the source of water that supports vegetation in meadow complexes in small alpine watersheds. Copyright © 2004 John Wiley & Sons, Ltd.     

A mirage at Regina

The Dirt Hills, located roughly forty miles to the southwest of the Regina Weather Office, at Regina, Saskatchewan, were clearly visible on the horizon in the early morning of the 29th day of August 1972 from the Regina Weather Office. This mirage was documented and a picture of it was taken.     

古亚洲洋东段闭合时限：来自大兴安岭南段二叠系-三叠系界线沉积地层和碎屑锆石年代学的制约

古亚洲洋东段的具体闭合时限长期以来存在争议,重要原因在于缺乏相应时期的典型沉积剖面研究。近期,笔者在大兴安岭南段阿鲁科尔沁旗地区新发现一套保存较好的二叠-三叠系沉积序列,其详细记录了古亚洲洋闭合过程。本文以此为研究对象,重点对上二叠统林西组和下三叠统老龙头组开展沉积学和碎屑锆石年代学研究。上二叠统林西组上部为一套湖泊相沉积,下三叠统老龙头组为一套河湖相沉积,底部为冲积扇辫状河砾岩层。两套地层界线附近沉积环境发生剧变,气候从温暖湿润转变为炎热干旱,确定研究区林西组沉积时代为晚二叠世长兴期,老龙头组沉积时代为早三叠世奥伦尼克期,两者为平行不整合接触关系,两者之间存在短暂沉积间断。林西组砂岩重矿物含量丰富,类型多样,原岩为中酸性岩浆岩、基性岩浆岩、少部分变质岩及沉积岩;老龙头组砂岩重矿物类型少,原岩为中酸性岩浆岩和少量变质岩。林西组2个碎屑岩样品最年轻峰值年龄分别为255±2Ma和255±1Ma,ε_Hf(t)=-22.84~+13.17,变化范围较大。老龙头组2个碎屑岩样品最年轻峰值年龄分别为248±1Ma和249±1Ma,ε_Hf(t)=7.95~11.28。结合重矿物、碎屑锆石和Hf同位素研究,确定林西组物源主要来自于兴蒙造山带,少量可能来自于华北板块,具有复杂物源、远距离搬运再沉积的特征。老龙头组物源主要来自于兴蒙造山带,具有周缘近距离搬运沉积的特征。通过区域对比上二叠统林西组与下三叠统老龙头组碎屑锆石携带年代学信息,推测古亚洲洋东段沿着西拉木伦河缝合带在晚二叠世发生汇聚碰撞作用,古亚洲洋东段闭合作用至少持续至早三叠世,老龙头组沉积期发生强烈汇聚造山作用,老龙头组是古亚洲洋闭合板块碰撞作用的产物。

     

青海明长城烽火台病害发育与海拔相关性研究

青海省明长城历经千百年风雨侵蚀和人为破坏,大多已消失殆尽,仅剩极少部分以土遗址的形式存在。经有关研究表明,明长城土遗址主要发育有包括片状剥离、冲沟、掏蚀、坍塌、裂隙、洞穴以及生物病害等6种典型类型。作为明长城的一种特殊建筑类型,烽火台主要具有传输信息的军事功能,其大多分布于高海拔地区。本文遴选分布于青海省湟中地区17座烽火台,对其病害发育进行现场勘查,并收集相关海拔资料,对烽火台病害发育与海拔进行拟合,旨在探究海拔对烽火台病害发育的影响。通过系统分析得出海拔对生物病害、片状剥离、洞穴以及掏蚀等4种典型病害影响存在一定影响,其中对片状剥离、洞穴以及掏蚀3种病害影响尤为显著,本研究为土遗址病害发育机理研究提供一种新的思路,并为青海省明长城文物保护工作提供有益参考。     

Detecting subtle hydrochemical anomalies with multivariate statistics: an example from ‘homogeneous’ groundwaters in the Great Artesian Basin,Australia

The major ion composition of Great Artesian Basin groundwater in the lower Namoi River valley is relatively homogeneous in chemical composition. Traditional graphical techniques have been combined with multivariate statistical methods to determine whether subtle differences in the chemical composition of these waters can be delineated. Hierarchical cluster analysis and principal components analysis were successful in delineating minor variations within the groundwaters of the study area that were not visually identified in the graphical techniques applied. Hydrochemical interpretation allowed geochemical processes to be identified in each statistically defined water type and illustrated how these groundwaters differ from one another. Three main geochemical processes were identified in the groundwaters: ion exchange, precipitation, and mixing between waters from different sources. Both statistical methods delineated an anomalous sample suspected of being influenced by magmatic CO₂ input. The use of statistical methods to complement traditional graphical techniques for waters appearing homogeneous is emphasized for all investigations of this type. Copyright © 2006 John Wiley & Sons, Ltd.     

车辆行驶振动对古长城影响分析及评价

交通振动会对周边古建筑产生不利影响,研究振动规律对古建筑的稳定性评价非常重要。为此,利用振动探测仪采集古长城因周边道路车辆行驶引起的振动数据。通过解译振动波形了解场地的振动强度衰减过程及大小,确定振动强度及对长城的影响,以及各因素与振动强度的关系。以国家古建筑允许振动规范对波形解译结果进行评价,为解决此类文明遗址的保护问题提供了技术支撑。分析结果表明:不同路况,振动衰减规律不同,路况较好振动强度衰减迅速;行驶车辆的车速、荷载及行驶道路质量均可影响长城水平振动强度,车速越快、荷载越大、道路质量越差,长城水平振动强度越大;长城不同位置对车辆行驶产生的振动响应不同,长城脚水平振动强度大于长城顶水平振动强度。     

北京城区河湖水质分析

调研结果显示,2003年北京城区河湖(11个监测水体)总磷、总氮含量分别为0．142mg/L、1．481mg/L,已达到比较 严重的富营养状态．北京城市河湖属于藻型水体,初级生产力主要决定于浮游藻类的群落结构与密度．河湖水体中浮游 藻类密度为37867．82×10~4cells/L,其群落由蓝藻(Cyanophyta)、绿藻(Chlorophyta)、硅藻(Bcillariophyta)、甲藻(Pyrrophy— ta)、隐藻(Cryptophyta)、黄藻(Xanthophyta)、金藻(Chrysophyta)和裸藻(Eugleniphyta)构成．群落中蓝藻占绝对优势 (89．54%)．在近几年的夏秋季连续发生程度不同的微囊藻(microcystis)水华,对水体功能和城市景观造成了不良影响． 主要原因是：(1)氮磷和有机物的污染,(2)给城市河湖补给的水量少,(3)河湖生态系统被损害,水体自净能力差．本文 对如何改善北京城市河湖水质提出了建议．     

The world''s large lake basins as denudation-accumulation systems and implications for their lifetimes

The mechanical denudation rates of 81 large lake basins (lake area > 500 km²) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described.