微地形条件下地表填洼量计算方法研究

地表填洼量是地表相对低洼处蓄存的水量,与地表径流与土壤侵蚀过程有直接关系。本文通过模拟黄土坡耕地普遍采用的人工锄耕和人工掏挖耕作措施下地表特征,探讨了地表填洼量的计算方法。结果表明：地表洼地空间分布较随机,人工掏挖措施下呈斑点大而少,人工锄耕下斑点小而多的特征;地表填洼量与坡面洼地面积呈显著正变函数关系,可以作为研究区坡耕地上人工锄耕和人工掏挖措施下地表填洼量的计算公式。     

晚中新世以来中国北方风成沉积的磁性地层学和沉积学研究及其古气候意义(英)

对黄土高原的灵台和泾川黄土 -红粘土序列进行了磁性地层学和沉积学研究.古地磁研究表明,泾川剖面的底界年龄为 8.0Ma,这比灵台剖面的底界年龄老 1.0Ma.通过空间上红粘土剖面的地层对比,发现灵台红粘土序列相对较为完整和连续.该剖面可以作为中国北方晚第三纪红粘土的标准剖面.野外观察和粒度分析均表明灵台和泾川红粘土沉积为风成沉积.通过对南北向黄土大断面粒度参数的系统分析,初步建立了 粉尘沉积的粒度参数———沉积区距源区最小距离"的半定量模型.根据这些模型推测,红粘土的主要源区可能在现代的巴丹吉林沙漠及其以西地区.灵台剖面的游离铁/全铁值变化表明,晚中新世以来东亚夏季风经历了非线性的演化历史.约 4.1～ 4.8Ma间为黄土高原地区 7.0Ma以来东亚夏季风最为强盛的时期.该气候事件的出现可能同全球温度背景较高及全球冰量较小有着动力学上的联系.     

THE DISCOVERY OF THE 400,000 YEARS CLIMATIC PERIOD IN CHINESE LOESS AND ITS BEARING ON PALEOCLIMATE

Magnetic susceptibility measurement was conducted at every10cm interval in the Baoji section,a 160 m thick loess-paleosoldeposit near the city of Baoji,Shaanxi Province.An independent timescale was constructed under control of geomagnetic polarity reversals byassuming that each paleosol and its underlying loess between twopaleomagnetic controls is a basic unit for linear interpolation based ontheir thickness,which indicate that the sediments represent the geologicalinterval 0 to 2.5 Ma BP.Fourier power spectra of the susceptibilitytime series monitor strong peak at quasi-period of 400 ka,which is dueto the eccentricity of the Earth's orbit,as well as 100 ka,40 ka and20 ka periods,in agreement with the astronomical theory of climaticforcing.A primary mode for the Matuyama climatic history is sum-marized as periodic 400 ka fluctuations superimposed by variation ofshorter periods,in the lower Matuyama,the dominant shorter period is100 ka cycle while 40 ka cycle in the upper Matuyama.     

A TENTATIVE CORRELATION OF CLIMATE CHANGES BETWEEN CENTRAL CHINA AND HIGH LATITUDE IN THE NORTH HEMISPHERE

１ＩｎｔｒｏｄｕｃｔｉｏｎＬｏｅｓｓｄｅｐｏｓｉｔｓａｒｅａｋｉｎｄｏｆｔｙｐｉｃａｌｔｅｒｒｅｓｔｒｉａｌｓｅｄｉｍｅｎｔｓｗｉｄｅｓｐｒｅａｄ,ｃｏｖｅｒｉｎｇａｂｏｕｔ１０ｐｅｒｃｅｎｔｏｆｌａｎｄｓｕｒｆａｃｅｏｆｔｈｅＥａｒｔｈ．Ｔｈｅｍａ...     

黄土中粘土矿物的提取及其对氯吡硫磷的吸附行为研究

以黄土为原料并从中提取粘土矿物,研究粘土矿物对氯吡硫磷的吸附行为,并从吸附等温线,动力学和热力学角度对其吸附机理进行探讨.吸附等温线模型研究表明,粘土矿物对氯吡硫磷的吸附属于Langmuir和Freundlich的复合型吸附;吸附动力学模型研究表明,该过程符合拟二级动力学方程;吸附热力学参数研究表明,该过程是一个自发的吸热反应,且主要作用为氢键吸附.研究结果有助于进一步探究土壤中残留农药的自净机理.     

大学生创新训练项目实践效果之思考--以“黄土滑坡早期识别与分级防治技术”项目为例

本文以“黄土滑坡早期识别与分级防治技术”项目为例,探讨性地分析了大学生创新训练项目所应选择的实施方式和实践效果,间接阐述了此类项目对大学生在完善专业理论知识和发展专业实践技能等方面的积极影响和促进作用。     

中国黄土高原生态型现代农业研究与实践

黄土高原是中国生态最为脆弱和经济最为贫困的地区之一,干旱缺水与水土流失并存是制约其健康发展的关键。本文以地处黄土高原丘陵沟壑区的榆林市米脂县孟岔村为研究基地,以山地红枣为研究对象与技术示范平台．通过长期定位试验研究、技术创新与集成、技术示范与培训,构建了以山地红枣矮化密植栽培技术和山地红枣微灌节水技术为核心,山地雨水就地集蓄利用技术、山地枣园土壤保墒技术和山地果园高效施肥技术为配套的陕北山地红枣集雨微灌工程技术体系,形成了“生态型现代农业发展模式”。“生态型现代农业发展模式”创建与实施,实现了黄土高原生态建设与经济发展的统一,为解决黄土高原水土流失与干旱缺水两大瓶颈问题提供了新的途径,为黄土高原可持续发展提供了一种新的思路。     

Iron in the NEEM ice core relative to Asian loess records over the last glacial–interglacial cycle

Mineral dust can indirectly affect the climate by supplying bioavailable iron (Fe) to the ocean. Here, we present the records of dissolved Fe (DFe) and total Fe (TDFe) in North Greenland Eemian Ice Drilling (NEEM) ice core over the past 110 kyr BP. The Fe records are significantly negatively correlated with the carbon-dioxide (CO₂) concentrations during cold periods. The results suggest that the changes in Fe fluxes over the past 110 kyr BP in the NEEM ice core are consistent with those in Chinese loess records because the mineral-dust distribution is controlled by the East Asian deserts. Furthermore, the variations in the dust input on a global scale are most likely driven by changes in solar radiation during the last glacial–interglacial cycle in response to Earth''s orbital cycles. In the last glacial–interglacial cycle, the DFe/TDFe ratios were higher during the warm periods (following the post-Industrial Revolution and during the Holocene and last interglacial period) than during the main cold period (i.e. the last glacial maximum (LGM)), indicating that the aeolian input of iron and the iron fertilization effect on the oceans have a non-linear relationship during different periods. Although the burning of biomass aerosols has released large amounts of DFe since the Industrial Revolution, no significant responses are observed in the DFe and TDFe variations during this period, indicating that severe anthropogenic contamination has no significant effect on the DFe (TDFe) release in the NEEM ice core.     

湿陷性黄土地基处理方案之比较

陕西关中地区大多为湿陷性或自重湿陷性黄土,在工程建设中,地基处理方案的确定往往需要慎之又慎．随着建筑物抗震等级的提高,也为地基处理提出了更高要求。本文通过关中地区某工程自重湿陷性黄土地基处理方案的比较,提出了技术上可行、经济上合理的处理方案．收到了良好的效果。     

静力触探技术在黄土地区工程勘察中的应用

静力触探技术经过70余年的发展及日趋完善,其操作简单,智能化程度高,是岩土工程勘察常用的原位测试手段之一。静力触探基本原理就是通过探头传感器实现一系列量的转化,并由仪器记录下来,达到测定土强度和其它指标之目的。本文一方面重点论述了静力触探技术在黄土地区勘察中的应用：根据地区黄土地层特点和经验建立了确定地基土承载力的经验公式及其它有关力学参数;详细地论述了如何依据静力触探参数判别土的类别、划分地层界线、确定地下水位埋深和地下洞穴等。特别是依据静力触探参数和曲线形态判别地下洞穴和确定地下水位是本领域的创新和发展。