Chemical Composition of Water along the Seashore and Front Delta of the Don River under Low-Water Conditions (20th–21st Centuries)

Doklady Earth Sciences - This study is based on the results of targeted water sampling undertaken at different weather conditions and water levels in the Don River delta and the seashore. The main...     

Pleistocene paleoecology of the Don and Scarborough Formations, Toronto, Canada, based on cladoceran microfossils at the Don Valley Brickyard

Cladoceran microfossil evidence has confirmed that a disjunction in environmental conditions existed during deposition of the Don and Scarborough Formations in Toronto, Ontario. Although mean annual temperatures were distinctly warmer during the Don interval than in the Scarborough, they were probably similar to the present-day regime. The cladoceran community was almost exclusively composed of littoral species throughout the sequence, suggesting that the deposition site was a shallow-water lentic habitat. Chydorid cladoceran species richness in the Don Formation averaged four times that in the Scarborough. Past community structure, water depth, and trophic state changes at the site were reconstructed from the proportions of littoral to planktic species, the proportions of sediment- to vegetation-preferring chydorids, and the species diversity and equitability.     

喀斯特山区药用栽培植物水土流失防治功能的Fuzzy评价

为了在评价喀斯特山地发展药用植物种植产业化的水土流失防治功能价值,本文在西南喀斯特腹地毕节市七星关区岔河镇足纳村石灰岩发育的黄壤坡地的泥沙侵蚀监测小区,分别栽培种植刺梨、金荞麦、刺梨套种头花蓼、刺梨套种何首乌、刺梨套种金荞麦,通过2016年和2017年两年雨季的监测,发现土壤侵蚀量与植物覆盖度、植物枝叶层厚度呈指数函数关系,与植物根系条数呈直线关系。进一步建立土壤侵蚀量与植物覆盖度、植物枝叶层厚度、植物根系条数的隶属函数,运用Fuzzy评价模型,对调查的20种药用植物的水土保持功能进行评价。结果表明:水土保持防治功能强的植物为刺梨、白芨,较强的植物有川乌、重楼、党参、山慈姑,其他均具有中等水土保持功能,并能按评价结果选择不同强度水土流失地段的药用适宜栽培植物,也较为符合调查区实际。      

Heavy metal flows in aquatic systems of the Don and Kuban river deltas

This paper presents the calculated heavy metal (Fe, Mn, Zn, Ni, Cu, Cr, Co, Cd, and Pb) flows in suspended and dissolved forms in the main navigable branches of the Don and Kuban river deltas during the low-water period of 2013–2014. This work is based on the data of field studies in which water and suspended matter samples were collected and the turbidity and water discharge in deltas were measured. A quantitative estimate of heavy metal inflows into the deltas of the Don and Kuban rivers is provided. Transformation of flows of suspended and dissolved metal forms from the delta top to the sea edge is discussed. The influence of localities (Rostov-on-Don, Temryuk) on the increase in heavy metal flows downstream is shown, and the heavy metal flows in the deltas of the Don and Kuban rivers are compared.

     

Contribution of Climatic and Anthropogenic Factors to Changes in the Flow of Large Rivers of the Russian Plain and Siberia

Doklady Earth Sciences - Changes in the annual and seasonal flow of the Volga, Don, Yenisei, and Lena rivers were estimated by two independent methods. One of them is based on the data of water...     

New finding of the ancient whale <Emphasis Type="Italic">Basilosaurus</Emphasis> (Cetacea,Archaeoceti: Basilosauridae) in the Lower Don area

The taxonomy and stratigraphic location of new remains of an ancient whale (Basilosaurus) discovered on the western coast of the Tsymlyansk water reservoir are considered. The Kharkov Formation deposits containing these remains are described, and their age is substantiated. The Basilosaurus remains discovered in the Lower Don area indicate that in the Late Eocene the ocean covered the southern part of the Russian Platform almost entirely.     

隧道围岩内地下水渗流边界效应影响研究

根据水位条件、施工工艺和防排水设计原则将隧道渗流计算围岩透水边界条件大致划分为4种类型,并分析了不同透水边界条件适应的施工工况。基于复变函数理论和保角映射方法,推导得出4种透水边界条件下隧道围岩内任一点孔隙水压力和隧道涌水量解析计算公式,通过与数值解的对比,印证了解析解的准确性。在此基础上,根据不同透水边界条件下隧道涌水量和围岩关键点孔隙水压力随埋深直径比（ ）的变化规律,分析了透水边界条件的变化对浅埋隧道和深埋隧道的影响,并探讨了浅埋水下隧道渗流计算中透水边界条件的选取。相关结论与认识对于隧道渗流计算和排水设计具有一定的指导作用和参考价值。     

Precipitation reconstruction using ring-width chronology of himalayan cedar from western himalaya: Preliminary results

Himalayan cedar (Cedrus deodara (D. Don) G. Don) due to its long age and wide ecological amplitude in the Himalayan region has strong dendroclimatic potential. A well replicated ring-width chronology of it, derived from the ensemble of tree-ring samples of two adjacent homogeneous sites, has been used to reconstruct precipitation for the non-monsoon months (previous year October to concurrent May) back to AD 1171. This provides the first record of hydrological conditions for the western Himalayan region, India during the whole of the ‘Little Ice Age’ and latter part of the ‘Medieval Warm Period’. The reconstruction revealed the wettest and the driest non-monsoon months during the fourteenth and the thirteenth centuries, respectively. The seventeenth century consistently recorded dry non-monsoon months in the western Himalayan region. Surplus precipitation, especially more pronounced since the 1950s, is recorded in the current century.     

Specific Features of Lithological and Mineralogical Compositions of Moraines in the Don Region

Results of the detailed lithological-mineralogical study of moraines from the well-known key sections in the Don Basin are presented. Important debatable issues concerning the age of Early Pleistocene glacial sediments are considered. Together with biostratigraphic data, recent data on the mineral composition of key moraine units can be used for solving these issues. The layered moraine sequence of the Don Basin (hereafter, Don moraine) shows compositional similarity in a regional scale. However, it is characterized by a spatiotemporal variation in the mineral and petrographic associations governed by specific paleogeographic settings and stages of moraine formation. Specific features of temporal rearrangement of these associations indicate the general paleogeographic trend of glacial lithogenesis. Therefore, they make it possible to compare moraines from the Kuznetsovka and Volnaya Vershina sections that include a combination of the most stable (and, generally, local) minerals and rocks of early stages of glacial lithogenesis. The compositionally most exotic Novokhopersk and Moiseevo moraines are logically attributed to the later stage of moraine formation. This does not contradict specific features of teriofauna in the interglacial sediments underlying and overlying the moraines. It is shown the spatiotemporal variation in the mineral composition of moraines of the Don region can be used for their stratigraphic correlation.__________Translated from Litologiya i Poleznye Iskopaemye, No. 3, 2005, pp. 321–332.Original Russian Text Copyright © 2005 by Bylinskii, Ananeva, Sudakova.     

范各庄矿12煤底板突水过程模拟分析

以范各庄煤矿水文地质条件为基础,建立了承压水上采煤的岩体水力学模型,应用岩石破裂过程渗流-应力耦合分析系统(RFPA2D-Flow)模拟分析了范各庄矿12煤层底板开采扰动下,裂隙形成、扩展到突水通道最终贯通形成突水的全过程。通过对损伤区分布、应力场和渗流场的演化分析,揭示了开采扰动及水压驱动下完整泥岩底板由隔水岩层到突水通道的演化过程,对突水通道进行了模拟定位,并对不同水压条件下含水砂岩层对底板突水的影响进行了分析。结果表明:12煤底板突水问题取决于含水砂岩中的水压力,在假设隔水层厚度不变时,水压力与突水系数呈正相关关系,随着水压的增大突水越易发生。该研究为12煤底板突水预测与防治提供了理论依据。      

Modeling the composition of mine (Waste Rock) water at the deposits of the Balkhach gold-bearing field

Modeling of hydrogeochemical processes in the rock-water system showed that the concentrations of Al, Fe, Sb, Sr, and W do not exceed the MAC levels even under conditions of prolonged interaction between water and rock minerals (R/W > 0.0001). The concentrations of As, Cd, Co, and Se are unlikely to significantly exceed the MAC even at decreasing rates of water exchange (at increasing R/W) owing to the low concentrations of these elements in the rocks of the deposit. The concentrations of Mn are likely to exceed the MAC level under reducing conditions, while they remain well within the MAC under weakly to moderately oxidizing conditions. A different situation is for Cr and S, which may be well above the MAC under oxidizing conditions and below the MAC under reducing conditions, when weakly oxidized species of S and Cr predominate. Model and measured concentrations of Cu, Mo, Ni, Pb, V, and Zn are generally similar to each other and to the MAC levels, but they may considerably exceed the MAC in the case of reduction in water exchange rates (longer duration of water-rock interaction and higher R/W). The concentrations of Cu, Mo, Ni, Pb, V, Zn, and Cr may exceed the MAC levels in the case of the prolonged exposure of strongly disintegrated rocks to moist air, whereas the wet environment is favorable for Mn hydroxide precipitation.     

水库滑坡地下水动态响应规律及浸润线计算模型

库水和降雨直接导致水库滑坡地下水变动,是诱发滑坡的主要因素。已有研究大多是基于监测数据探讨库水与降雨对滑坡变形的影响,未能揭示水库滑坡地下水响应规律,地下水浸润线计算模型没有同时考虑降雨和库水的影响,且模型边界条件与水库滑坡实际情况差别较大。为了揭示大型水库滑坡地下水动态响应规律,需要构建更接近实际情况的地下水位浸润线计算模型。通过三峡水库石榴树包滑坡地下水动态监测,揭示了库水水位变化和降雨条件下滑坡地下水水位动态响应规律,其地下水渗流场近似层流,滑坡前缘和中部的地下水水位与库水位几乎同步,滑坡后部的地下水水位主要受降雨影响,日降雨30 mm会引发地下水水位明显变动。在周期性库水位变化和随机降雨耦合条件下,建立了滑坡地下水非稳定渗流微分方程,解算出水库滑坡地下水位浸润线计算模型,并采用实际监测结果进行了验证。应用计算模型分析了不同工况条件下的滑坡渗流场,并得出滑坡内距前缘水平距离145 m内,库水对地下水有影响;引发地下水变动的降雨和库水位变化阈值分别为0.03,0.1 m/d,且不同的条件组合下降雨和库水位对地下水水位影响存在一定差异。     

不同荷载条件下冻土融化沉降过程试验研究

融沉是困扰多年冻土区工程建设与安全运营的关键因素之一。通过室内试验,针对两种初始干密度不同的青藏粉质黏土,在-8~24 ℃之间正弦波动的周期温度边界条件下,分别开展了无荷载、静荷载及动荷载作用下冻结饱和试样的融沉试验（试样的初始温度为-1 ℃）,研究了试样内部温度、变形、孔隙水压力的时间变化过程。结果表明：温度边界相同时,在不同荷载作用下试样内部温度响应过程差异显著,反映了荷载对冻土融化速率的影响。在无荷载作用下,试样的竖向变形呈线性发展趋势,每次冻融过程中的融沉变形变化不大。在静荷载和动荷载作用下,试样的竖向变形呈先快速增加后逐渐稳定的趋势,且融化沉降变形主要发生在前3~4个冻融循环过程。试验结束时,在静、动荷载作用下试样最终变形量大于无荷载作用下,且干密度较小时竖向变形较大。在动荷载作用下,试样内部孔隙水压力变化幅度大于静荷载,且在前3次冻融循环过程中,动荷载作用下试样内部孔隙水压力消散数值大于静荷载,之后随着冻融循环次数的增加两者差异逐渐减小。试样融沉变形过程与温度变化、孔隙水压力的积累和消散过程密切相关。试验结果可为复杂边界条件下融化固结理论研究和工程中地基土体的融沉变形预测提供依据。     

污水环境对水泥土渗透性能影响的试验研究

现多数水泥土防渗工程都间接或直接的与地下腐蚀性介质环境接触,会导致水泥土防渗性能的降低甚至失效。因此,通过室内模拟试验,设计了不同的水泥掺入比,进行了在污水和清水环境下水泥土的渗透性能试验,研究了在不同龄期下水泥土的渗透系数变化规律,并同时分析了渗透后水泥土中离子浓度的变化规律。试验结果表明,在清水环境下,随着龄期的增长,水泥土的渗透系数逐步减小,60 d后随着龄期的增加,水泥土渗透系数减小的程度越来越缓慢;在污水养护条件下,龄期在60 d之前,水泥土渗透系数逐步减小,龄期在60 d之后,由于水泥土被侵蚀,致使水泥土随着龄期的增加,水泥土的渗透系数逐步增大;无论是清水还是污水环境,随着水泥掺量的增大,其渗透系数均逐步降低;在污水环境中,随着龄期的增加,其水泥土中的Ca2+,Mg2+,Cl?, 浓度均逐步增大,而清水环境中Mg2+,Cl?, 浓度均逐步减小。其研究成果可为水泥土防渗工程的抗渗性和耐久性设计和应用提供技术参数,具有重要的工程意义。     

Mineral composition of the fine-dispersed fractions of loess and soil processes developed in them

Of the stable indications of elementary soil processes those are to be identified which are taking place in the fine-dispersed fractions of soil by transformations of layer silicates and primarily of interstratified formations.Instrumental detection of transformations in the fine-dispersed material and of its migration along paleosol profiles allows a comparison with changes in recent soils and a judgement about the conditions of paleosol formation. This presumption is supported by data on the mineral composition of the fine-dispersed fractions of the Mikulino interglacial soils as a product of the first phase of pedogenesis within the Mezin loess- paleosol complex (Morozova et al. 1979) and, in general, of the loess-paleosol sequence developed above the ground moraine of the Don glacier tongue containing paleosols formed in the Early, Middle and Late Pleistocene (Velichko et al. 1965).     

茨菇滑坡滑带土扰动样强度参数取值分析及滑坡稳定性评价

位于近坝库区的茨菇滑坡,在水库正常蓄水后有近1/3坡体浸没于水位面以下,蓄水前后的滑坡稳定性对工程影响很大。滑坡区地质环境条件复杂,滑坡成因机制为弯曲折断-滑移的地质力学模式。本文进行了对滑坡区扰动样滑带土在不同含水率条件下的剪切强度试验,试验结果表明,粘聚力与含水量相关性好,而摩擦系数则变化不大。结合极限平衡及有限元数值计算,对茨菇滑坡在蓄水前后天然、暴雨及地震工况条件下的稳定性进行分析。结果表明蓄水前滑坡处于稳定状态,水库蓄水以后,天然工况及暴雨工况下滑坡仍然处于稳定状态,地震工况下,滑坡的稳定性系数在1.0以下,滑坡可能失稳破坏。     

不同应力路径下非饱和黄土的结构变化特性

以陕西杨陵非饱和黄土为研究对象,对不同初始含水率的原状黄土及相应的重塑黄土进行不同应力比下的等应力比加载试验,求取非饱和黄土在不同应力状态下的综合结构势参数,研究了黄土在等应力比压缩试验状态下的结构变化特性。结果表明,当初始含水率不变时,应力比(?=?3/?1)对黄土的结构性有较大的影响,表现为应力比愈小,黄土的结构性愈弱;当应力状态不变时,含水率对结构性参数影响明显。含水率愈低,同一应力状态下对应的结构性参数愈大,尤其在低含水率区域,含水率变化强烈影响原状黄土的结构性。     

煤矿采动条件下煤层气储层模型及应用

煤矿区煤层气开发受煤矿采动影响,为实现煤矿采动条件下煤层气井产能数值模拟,抽象概化了采动条件下煤层气开发的地质模型,构建了采动条件下煤层气储层的数学模型,并通过对CBM-SIM软件二次开发,实现了采动条件下煤层气储层的数值模拟。在建模和数值解算软件开发中,基于采动离层量变化曲线公式构建了采动条件下储层渗透率变化曲线公式,利用采动井水位变化规律构建了储层漏失水量变化公式,利用时间卡机制解决了煤储层渗透率及漏失水量的动态求解和循环迭代过程中作为系数和边界条件的调用赋值,实现了渗透率随采动影响的动态变化、储层水漏失降压和储层产气的耦合解算。应用开发的软件对淮南矿区某矿采动条件下煤层气抽采井生产数据进行历史拟合和产量模拟应用,预测煤层气产量曲线与实际生产曲线基本一致,判定系数达到0.92。      

降雨入渗影响下边坡中的非饱和渗流特性

为了分析降雨入渗影响下非饱和土坡渗流特性,利用自制降雨模拟系统和实时监测系统,对降雨诱发非饱和土坡失稳过程进行全方位、多参量的实时监测,研究不同降雨条件下,不同坡度、不同压实度边坡坡体不同位置雨水入渗率和湿润峰的实变规律.结果表明:降雨入渗条件下,陡坡和高压实度土体不利于雨水入渗,而缓坡和低密实度土体入渗率变化快;实际土体吸力和含水量实时变化规律不同步,提出试验湿润峰概念,含水率（吸力）湿润峰点可按含水率（吸力）实时曲线的过渡区和雨后残余含水率（吸力）的线性交叉点确定;考虑单向吸湿或脱湿路径下土体含水率和吸力具有唯一对应关系,含水率湿润峰点与吸力湿润峰点的绝对值时差即为形成湿润峰所需时间;对比湿润峰实测值与Lumb半经验值散点分布规律,基于Lumb湿润峰深度计算公式提出非线性修正表达式.