在“三水”转化过程中岩土水势梯度变化及其变化机理研究     

张光辉 《吉林大学学报(地球科学版)》1991,(2)

通过对岩土水势梯度特征性变及机理研究,进一步加深了对“三水”转变关系的了解,并对降水入渗补给地下水机制和潜水蒸发过程及有关水文地质问题有了新认识。  相似文献   

Dry Season Salinity Changes in Arid Estuaries Fringed by Mangroves and Saltflats   总被引：1，自引：0，他引：1  

P. V. Ridd  T. Stieglitz 《Estuarine, Coastal and Shelf Science》2002,54(6):1039

Mangrove swamps and hypersaline saltflats fringe many estuaries in dry tropical climates, especially in Northern Australia. For most of the year these estuaries receive zero riverine freshwater input and thus, after the wet season, a steady increase in salinity occurs. In some locations the estuary becomes fully inverse, i.e. the salinity increases monotonically from the mouth to the head. In other locations, a salinity maximum zone separates the sea from low salinity water that persists at the head of the estuary throughout the dry season. Field data from five estuaries indicate that in short estuaries where a large area of saltflats and mangroves extends over the whole length of the estuary, the estuary becomes completely inverse with salinity rising to 55 within a couple of months. The evaporation and evapotranspiration over the saltflats and mangroves cause this rapid increase in salinity. Longer estuaries where a large area of salt flat exists only close to the mouth do not become completely hypersaline for the whole length of the estuary by the end of the dry season. A salinity-maximum is generated close to the river mouth but salinities of less than 10 persist in the upper reaches of the estuary until the end of the dry season, even though the estuary does not receive any further freshwater input. A simple analytical expression is presented that reproduces the changes in salinities in the estuaries studied. This model can be used to predict the formation of hypersaline conditions in other mangrove and saltflat fringed estuaries where freshwater flow is negligible.  相似文献   

Dynamics of evapotranspiration from a riparian pond complex in the Western Boreal Forest,Alberta, Canada     

R. M. Petrone  U. Silins  K. J. Devito 《水文研究》2007,21(11):1391-1401

The relative contributions to total actual evapotranspiration (AET) from pond and riparian areas in a pond‐wetland complex in the Western Boreal Plain (WBP) of northern Alberta are measured using the Bowen ratio energy balance technique. Measurements show that a pond typical of the WBP evaporates at a rate more than twice that of the adjacent riparian peatland. Relating the actual to potential evapotranspiration over both surfaces yields Priestley–Taylor α coefficients of 0·69 and 1·11 for the peatland and pond respectively. Further results demonstrate that the sheltering and turbulent influences of the adjacent forested areas must be considered in the processes governing the permanence of WBP ponds. That is, forestry practices may inadvertently enhance the evaporative losses from the ponds, over and above the controls exerted by the regional climate. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

Modelling hourly and daily open‐water evaporation rates in areas with an equatorial climate     

Stephen Boon Kean Tan  Eng Ban Shuy  Lloyd Hock Chye Chua 《水文研究》2007,21(4):486-499

Evaporation rate estimation is important for water resource studies. Previous studies have shown that the radiation‐based models, mass transfer models, temperature‐based models and artificial neural network (ANN) models generally perform well for areas with a temperate climate. This study evaluates the applicability of these models in estimating hourly and daily evaporation rates for an area with an equatorial climate. Unlike in temperate regions, solar radiation was found to correlate best with pan evaporation on both the hourly and daily time‐scales. Relative humidity becomes a significant factor on a daily time‐scale. Among the simplified models, only the radiation‐based models were found to be applicable for modelling the hourly and daily evaporations. ANN models are generally more accurate than the simplified models if an appropriate network architecture is selected and a sufficient number of data points are used for training the network. ANN modelling becomes more relevant when both the energy‐ and aerodynamics‐driven mechanisms dominate, as the radiation and the mass transfer models are incapable of producing reliable evaporation estimates under this circumstance. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

东营凹陷岩盐成矿条件浅析     

孙文广  刘丰武  彭文泉  蒋波  高庆  王峰  赵海滨 《山东地质》2009,(3):27-30

东营凹陷是一个中、新生代断落凹陷区,发育了巨厚的新生代地层。凹陷内岩盐主要发育在沙河街组四段中下部,通过对沉积盆地演化阶段、岩盐赋存层位及蒸发岩系序列结构的分析,指出岩盐是在陆相环境中沉积的,属海源陆相沉积矿床。  相似文献   

塔里木盆地西北部不同类型蒸发器水面蒸发变化趋势分析   总被引：2，自引：1，他引：1  

马金玲  周宏飞 《干旱区地理》2005,28(3):300-304

根据位于塔里木盆地西北部的阿克苏水平衡试验站3种不同类型水面蒸发器Ф20cm、20m^2和E601型的实测水面蒸发资料,对水面蒸发变化趋势进行了分析。从1982—1988年Ф20cm、20m^2和E601型三种仪器测得的蒸发值均是逐年减少的,而1990-2003年三种仪器测得的蒸发值也足逐年减少的。1966-1988年Ф20cm蒸发皿蒸发量有增加的趋势,造成增加的主要原因足风速的增加。蒸发肌蒸发量的增加主要表现在夏季,其次为秋季和冬季,春季的增加趋势不明显。  相似文献   

Heating experiments relevant to the depletion of Na,K and Mn in the Earth and other planetary bodies     

《Chemie der Erde / Geochemistry》2019,79(4):125540

We have studied the evaporation of Na, K and Mn from Al-Na-K- and Mn-rich silicates at various conditions. Total alkali oxide contents ranged from 5 to 20%. The evaporation rate of Na increases with temperature and decreasing oxygen fugacity and decreases with duration of heating. The loss of K is in all cases less pronounced than for Na. Heating in an evacuated vacuum furnace is more effective in removing Na and K from melt droplets than in furnaces with one atm gas flow of air or gas mixtures controlling the oxygen fugacity. The strong pumping required to keep the vacuum removes Na and K atoms very effectively. In all experiments, the rate of evaporation is determined by quasi-equilibrium between a thin layer of Na and K rich gas above the molten silicates. The results of the experiments are in agreement with several other studies.In experiments with more than one sample in the furnace, equilibration of Na- and K-rich samples with Na- and K-poor samples occurred rapidly, mediated by the ambient gas phase.The results of experiments with Mn in starting compositions showed much stronger losses of Na than Mn under a variety of conditions.Thus the nearly chondritic Mn/Na ratios in the Earth cannot be the result of evaporation of Na and Mn in Earth-making materials, as the Mn/Na ratios in evaporation residues would be much higher than chondritic ratios. Such evaporation processes may have occurred in the parent material of Moon, Vesta and Mars.The data suggest, in agreement with earlier hypotheses, that the high and variable contents of Na and K in chondrules require a gas phase high in Na and K equilibrating with chondrule melts. The volume of nebular gas parental to a certain type of chondrites was heated and Na and K were lost from the chondrule precursors to the gas phase. Subsequently the nebular parcel was compressed leading to higher partial pressures of Na and K. Flash heating then produced chondrule melts which incorporated some of the gaseous Na and K and then cooled rapidly. The large range of Na and K contents in chondrule melts reflects very local enrichments of Na and K in the gas phase. Despite these variations bulk chondritic meteorites have well defined bulk Na and K contents, implying a closed system during formation of chondrules and matrix.  相似文献   

NaCl-X-H2O三元体系25℃等温蒸发石盐流体包裹体均一温度实验研究     

李俊  程怀德  张西营  李雯霞  海擎宇  张星  周同亮 《矿床地质》2019,38(1):120-128

复杂卤水组分对于石盐流体包裹体均一温度的影响尚不明确,文章基于NaCl-X-H_2O(X=KCl, MgCl_2,CaCl_2, Na_2SO_4)三元卤水体系,尝试探讨K~+、Mg~(2+)、Ca~(2+)、SO_4~(2-)对石盐流体包裹体均一温度测试结果的影响。不同卤水体系最大均一温度分析结果表明,K~+、Mg~(2+)、Ca~(2+)的存在总体上会导致石盐流体包裹体均一温度偏大,SO_4~(2-)的存在对均一温度的影响很小。以NaCl-H_2O体系为参照,NaCl-Na_2SO_4-H_2O体系平均均一温度较之要低,而NaCl-KCl-H_2O、NaCl-MgCl_2-H_2O和NaCl-CaCl_2-H_2O体系与其相反。NaCl-KCl-H_2O体系中的KCl浓度与平均均一温度呈现负相关关系,NaCl-MgCl_2-H_2O、NaCl-CaCl_2-H_2O、NaCl-Na_2SO_4-H_2O体系中的w(MgCl_2)、w(CaCl_2)和w(Na_2SO_4)与平均均一温度则呈现正相关关系。平均和最大均一温度分析结果都显示出复杂卤水体系中不同离子及其浓度对石盐流体包裹体均一温度会产生影响。本研究对于具有复杂化学组分卤水结晶析出石盐均一温度的研究具有重要的参考价值。  相似文献   

Dating of the Dachang Superlarge Tin-polymetallic Deposit in Guangxi and Its Implication for the Genesis of the No. 100 Orebody   总被引：4，自引：0，他引：4  

WANG Denghong  CHEN Yuchuan  CHEN Wen  SANG Haiqing  LI Huaqin  LU Yuanfa  CHEN Kaili  LIN Zhimao 《《地质学报》英文版》2004,78(2):452-458

The Dachang superlarge Sn-polymetal deposit in Guangxi, China, is one of the largest tin deposit all over the world. However, this deposit has long been in debate as to its origin. One of the opinions is that the Dachang deposit was formed by replacement of hydrothermal solution originating from Yanshanian granites, and the other is that this deposit was formed by submarine exhalation in the Devonian. This paper presents some new isotopic geochronology data obtained with the 40Ar-39Ar method for quartz and sanidine from massive ore in the No. 91 and No. 100 orebodies. Analytic results show that the No. 91 orebody was formed at 94.52±0.33 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz) or 91.4±2.9 Ma (the plateau age obtained with the 40Ar-39Ar method for feldspar), while the No. 100 orebody was formed at 94.56±0.45 Ma (the plateau age obtained with the 40Ar-39Ar method for quartz), suggesting that both the No. 91 and the No. 100 orebodies were formed at the Late Yanshanian instead o  相似文献   

西藏不同气候区域旱涝特征分析     

向毓意  杜军  马玉才 《气候与环境研究》2001,6(3):354-360

提出有效降水的概念,并将有效湿润度(有效降水与可能蒸发量的比值)的异常程度作为判别指标,对西藏高原不同气候区域的旱涝特征进行了研究.  相似文献