渭河流域东部全新世黄土-古土壤剖面光释光测年及其记录的土壤侵蚀事件   总被引：2，自引：0，他引：2  

贾耀锋  黄春长  庞奖励  毛龙江  葛本伟 《海洋地质与第四纪地质》2008,28(3)

在渭河流域东部老官台(LGT)全新世黄土-古土壤剖面中,系统采集了15个黄土释光测年样品,应用单片再生剂量法(SAR)对这些样品的细颗粒混合矿物进行了光释光(OSL)测年,测定结果表明:红外之后蓝光释光([post—IR]OSL)的年龄偏大,红外释光(IRSL)的年龄偏小或与蓝光释光(BLSL)的年龄基本一致,应用IRSL和BLSL信号测定的OSL年龄整体偏小可能与测定样品中长石矿物的异常衰退有关,而[post—IR]OSL信号由于很少发生异常衰退问题,使得其年龄可靠性更高。基于测定的[post-IR]OSL年龄,结合该剖面的磁化率和粒度指标,进一步探讨了渭河流域东部自全新世以来发生的两期土壤侵蚀事件,第1期土壤侵蚀事件发生在约12.40～9.34 kaBP,即全新世大暧期来临之前的气候转暖期间;第2期土壤侵蚀事件发生在约4.60～3.76 kaBP,即全新世大暖期即将结束、气候开始出现恶化、黄河中游地区夏文化发展的时期,这为深入探索夏代发生的大洪水事件及其气候背景提供了科学依据,本区两期显著的土壤侵蚀事件的发现,揭示了东亚季风系统的不稳定性,表现为千年到百年尺度上的快速变化。  相似文献   

Water source characterization through spatiotemporal patterns of major,minor and trace element stream concentrations in a complex,mesoscale German catchment     

Holger L. Fröhlich  Lutz Breuer  Hans‐Georg Frede  Johan A. Huisman  Kellie B. Vaché 《水文研究》2008,22(12):2028-2043

The link between spatiotemporal patterns of stream water chemistry and catchment characteristics for the mesoscale Dill catchment (692 km²) in Germany is explored to assess the catchment scale controls on water quality and to characterize water sources. In order to record the spatiotemporal pattern, ‘snapshot sampling’ was applied during low, mean and high flow, including 73 nested sites throughout the catchment. Water samples were analysed for the elements Li, B, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Mo, Ba, Pb and U using inductively‐coupled‐plasma mass spectrometry, and for electric conductivity and pH. Principle component analysis and hierarchical cluster analysis were used to find typical element associations and to group water samples according to their hydrochemical fingerprints. This revealed regional hydrochemical patterns of water quality which were subsequently related to catchment attributes to draw conclusions about the controls on stream chemistry. It was found that various lithologic signals and anthropogenic point source inputs controlled the base flow hydrochemistry. During increased flows, stream waters were diluted causing additional hydrochemical variability in response to heterogeneous precipitation inputs and differences in aquifer storage capacities. The hydrochemical patterns further displayed in‐stream mixing of waters. This implied, that stream waters could be apportioned to the identified water sources throughout the catchment. The basin‐wide hydrochemical variability has the potential to outrange the tracer signatures typically inferred in studies at the hillslope scale and is able to strongly influence the complexity of the catchment output. Both have to be considered for further catchment scale tracer and modelling work. Despite the likelihood of non‐conservative behaviour, the minor and trace elements enhanced the rather qualitative discrimination of the various groundwater types, as the major cations were strongly masked by point source inputs. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Seasonal,hydrological, and land management factors controlling dissolved organic carbon concentrations in the loch fleet catchments,Southwest Scotland     

Ian C. Grieve 《水文研究》1990,4(3):231-239

Dissolved organic carbon (DOC) was measured at hourly or two-hourly intervals during more than 30 events in one forested and two moorland subcatchments of the Loch Fleet catchment in southwest Scotland. The dominantly peaty soils in the catchments resulted in small discharge-related DOC variations within individual events, with a maximum range of about 2 mg 1^?1. Seasonal variations were larger with an amplitude of 8-9 mg 1^?1 and maximum concentrations in the summer months. The forested stream had the highest mean DOC, twice as large as the comparable moorland stream in the preliming phase. Applications of lime to the catchments increased stream DOC concentrations, with the largest increases in the moorland catchments.  相似文献   

Concentration–discharge relationships reflect chemostatic characteristics of US catchments     

Sarah E. Godsey  James W. Kirchner  David W. Clow 《水文研究》2009,23(13):1844-1864

Concentration–discharge relationships have been widely used as clues to the hydrochemical processes that control runoff chemistry. Here we examine concentration–discharge relationships for solutes produced primarily by mineral weathering in 59 geochemically diverse US catchments. We show that these catchments exhibit nearly chemostatic behaviour; their stream concentrations of weathering products such as Ca, Mg, Na, and Si typically vary by factors of only 3 to 20 while discharge varies by several orders of magnitude. Similar patterns are observed at the inter‐annual time scale. This behaviour implies that solute concentrations in stream water are not determined by simple dilution of a fixed solute flux by a variable flux of water, and that rates of solute production and/or mobilization must be nearly proportional to water fluxes, both on storm and inter‐annual timescales. We compared these catchments' concentration–discharge relationships to the predictions of several simple hydrological and geochemical models. Most of these models can be forced to approximately fit the observed concentration–discharge relationships, but often only by assuming unrealistic or internally inconsistent parameter values. We propose a new model that also fits the data and may be more robust. We suggest possible tests of the new model for future studies. The relative stability of concentration under widely varying discharge may help make aquatic environments habitable. It also implies that fluxes of weathering solutes in streams, and thus fluxes of alkalinity to the oceans, are determined primarily by water fluxes. Thus, hydrology may be a major driver of the ocean‐alkalinity feedback regulating climate change. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Application of the SHETRAN basin‐scale,landslide sediment yield model to the Llobregat basin,Spanish Pyrenees     

James C. Bathurst  Aidan Burton  Barry G. Clarke  Francesc Gallart 《水文研究》2006,20(14):3119-3138

The first application of the SHETRAN basin‐scale, landslide erosion and sediment yield model is carried out for a major landsliding event in the upper 505 km² of the Llobregat basin, in the eastern Spanish Pyrenees, in November 1982. The model simulates the spatial distribution of shallow landslides and their sediment yield. Acknowledging uncertainty in the model parameter evaluation, the aim of the application was not to reproduce the observed occurrence of landslides as accurately as possible with one simulation, but to bracket the observed pattern with several simulations representing uncertainty in the key input conditions. Bounds on the landslide simulations were thus determined as a function of uncertainty in the vegetation root cohesion (used in the model factor of safety calculations). The resulting upper bound considerably overestimates the observed pattern (17 000 landslides compared with an observation of around 700), but it reproduces several of the principal clusters in the observed pattern. The lower bound contains around 500 landslides. The sediment yield estimates (2670–14 630 t km^?2) are comparable to measurements elsewhere in the Pyrenees for extreme events. The results demonstrate an ability to simulate the basin‐scale landslide response to a rainfall event and the resulting sediment yield. They also highlight the need for further research in setting the uncertainty bounds and in avoiding large overestimates of landslide occurrence arising in part from a current inability to model small‐scale controls for a basin of the given size. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

渭河盆地西安凹陷地热田热储特征及开发方式     

刘润川  任战利  任文波  杨瑞涛  熊文学  白奋飞  王琨  李建明  王亚奇  张莹 《地质学报》2023,97(10):3456-3474

热源、热储层(砂体厚度、孔隙度、渗透率)、地温场等是影响地热资源评价的重要因素。本文以渭河盆地西安凹陷-西安市延长石油西化小区为例,在收集前人资料的基础上,应用地层测温、测井、岩芯分析等资料,分析了研究区地温场特征、热储层特征及地热资源量,运用多种参数对热储层有利区进行了综合评定。研究结果表明延长石油西化小区属地热异常区,地温梯度为3.5℃/100 m;研究区张家坡组、蓝田灞河组砂泥岩互层发育,砂厚分布在40～140 m之间,平均孔隙度分布在15.68%～30.3%之间,蓝田灞河组砂层厚度、地层热量、含水量和总热量均高于三门组和张家坡组地层,地热开发条件最好;综合考虑砂体厚度、地层含水量、地温梯度、地温、热储层物性因素,认为西安凹陷延长石油西化小区地热开发应选择蓝田灞河组为主要目的层段,最优的地热开发方式应采用采灌平衡法进行地热开采,综合考虑研究区更宜选择中深层地埋管井下换热方式进行地热资源开发。  相似文献   

大尺度平原城市精细汇水区分级划分研究     

王岩  范子贤  李成名  戴昭鑫  吴政 《测绘通报》2021,(7):117-120,125

在城市内涝模拟研究中,汇水区划分是十分重要的环节,同时对大尺度平原城市进行汇水区精细划分也是研究者共同研究的技术难点。针对现有基于DEM流向分析的划分方法存在的无法正确反映实际城市复杂地形和流向问题,本文提出了一种顾及地类和流向,适用于大尺度平原城市的精细汇水区分级划分方法。首先,从城市自然地形和主干河流出发,进行一级宏观尺度划分;然后,依据城市主次干道,干渠和管网实现二级中观尺度划分;最后,在二级划分的基础上,结合流向和地类做精细的三级子汇水区微观尺度划分。本文选取东营市30 km²核心主城区进行了验证分析,研究结果表明,划分结果跟实际地物类型和真实流向相吻合,该方法对于大尺度平原城市具有良好的适用性。  相似文献   

Intertidal sand‐dwelling Peracarid fauna of North Island,New Zealand     

A. A. Fincham 《新西兰海洋与淡水研究杂志》2013,47(4):677-696

Abstract

Substrate and infauna samples were taken at four tidal levels (mean high water springs, high mid beach, low mid beach, and mean low water neaps) with a 0.0625 m² quadrat at 14 North Island beaches in New Zealand. The distributions of Peracarida (Crustacea) were correlated with sediment type, tidal height, and degree of exposure; sampling began in March 1972 and was completed in November 1973.

Substrate samples were sieved and median diameter of the particles ranged from very coarse sand of — 0.60? to very fine sand of + 3.259?. Substrates were variously sorted: ? quartile deviation ranged from 0.14? to 0.66?, skewness from ‐ 0.08? to + 0.07?.

Peracarid fauna was moderately abundant; the maximum value was 720 animals per square metre on a fully exposed beach. Highest average abundance (303 per square metre) for the 14 beaches was recorded from the mean low water neap station. Amphipoda was the dominant group (54% of all Peracarida recorded), followed by Isopoda (33%) and Cumacea (13%). Frequency of occurrence at the 56 stations was headed by Amphipoda (64%), followed by Isopoda (46%), and Cumacea (20%).

The results are compared with data from Stewart Island beaches, and the biogeographical distributions of recorded Peracarida are discussed. An unexpectedly high degree of endemism exists for a warm‐temperate region, caused by the isolation of New Zealand, which has no direct shallow water contact with tropical or cold temperate regions.  相似文献   

Distribution and Forming Model of Fluvial Terrace in the Huangshui Catchment and its Tectonic Indication     

WANG Xianyan  LU Huayu  Jef Vandenberghe  CHEN Zhongyan  LI Langpin 《《地质学报》英文版》2010,84(2):415-423

<正>The Huang Shui River,a main tributary of the Yellow River,crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation.The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping.Three terraces in the Haiyan Basin,four terraces in the Huangyuan Basin,19 terraces in the Xi'ning Basin(the four high terraces may belong to another river),nine terraces in the Ping'an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized.Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River,which is located at the margin of Tibet,are different from that of the rivers at other regions.The formation process of the terrace is more complicated at the Huang Shui catchment:both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins,indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins.A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper.First,the equilibrium state of the river is broken because of climatic change and/or tectonic movement,and the river incises in all basins in the whole catchment until reaching a new equilibrium state.Then,the downstream basin subsides quickly and the equilibrium state is broken again,and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again.Finally,the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins.The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment.These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin.Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.  相似文献   

渭河流域地表水可利用量分析计算     

井涌 《水文》2010,30(1)

地表水可利用量是流域和区域水资源规划的重要指标.本文应用断面过流量减去河道内生态需用水量与河道外难控制利用弃水量,并扣除二者间重复计算量的算法,利用华县、状头两个水文站断面实测和统计数据,分析计算渭河多年平均地表水可利用量为54.91亿～66.33亿m~3/a.  相似文献