A partial explanation of the dependency of hydraulic conductivity on positive pore water pressure in peat soils     

Andrew J. Baird  Simon W. Gaffney 《地球表面变化过程与地形》1995,20(6):561-566

Part of the relationship between positive pore water pressures and hydraulic conductivity in peat soils may be explained by accumulations of methane bubbles. We show how compression and expansion of gas bubbles with changes in pore water pressure could cause changes in hydraulic conductivity and thus help to explain some observations of dependency of hydraulic conductivity in peats on pore water pressure. Consideration is also given to the effect on hydraulic conductivities of methane gas going into solution with increase in pore water pressure.  相似文献   

尖晶石中的Si含量及其存在形式     

李建平  Hugh. St.C. O''Neill 《岩石矿物学杂志》1995,14(3):230-235

自然岩石及简单和复杂体系中实验合成或经重新平衡的尖晶石化学成分显示，在中－低压条件下，与橄榄石共存的尖晶石可含一定量的Ｓｉ，其含量随温度和压力的升高而增大。用最小二乘法对简单体系中 实验数据的热力学模拟发现，Ｓｉ在铬尖晶石中以硅酸盐尖晶石（Ｍｇ２ＳｉＯ４）形式存在，Ｍｇ２ＳｉＯ４组份在铬尖晶石中的活度ａＳＤＭＧ２ＳｉＯ４＝（ＮＳＰＭＧ／２）２＊（ＮＳＰＳｉ）２（ＮＳＰＳｉ代表以４个氧为基础的单位尖  相似文献   

Determining past atmospheric HCl mixing ratios from ice core analyses     

Florent Dominé  Emmanuel Thibert  Eric Silvente  Michel Legrand  Jean-Luc Jaffrezo 《Journal of Atmospheric Chemistry》1995,21(2):165-186

Laboratory and field measurements have been performed in order to improve our understanding of the HCl air-snow transfer function. The solubility and diffusion of HCl in laboratory grown single crystals of ice have been measured as a function of HCl partial pressure,P _HCl, between –8 and –25 °C. Measurements ofP _HCl and of the mole fraction of HCl in snow,X'_HCl, have been measured at Summit, Greenland. Comparison of the field and laboratory measurements show that theX'_HCl values are well below equilibrium values. The major processes involved in the formation of snow crystals and in their evolution after deposition are discussed in order to attempt to understand theX'_HCl values and their variations. The discussion is focussed on a few well identified snow layers. It is concluded that sublimation and recrystallization of snow probably play a major role in the evolution ofX'_HCl, but that our understanding of the HCl transfer function is very incomplete. Laboratory and field measurements are suggested to improve this situation.  相似文献   

Au在SiO2—HCl—H2O体系中200℃溶解度测定：硅化对金矿化的意义初探   总被引：8，自引：2，他引：8  

王声远  樊文苓 《矿物学报》1994,14(1):46-55

实验标定了200℃时Au与SiO2间的络合反应：热力学计算表明，在具地质意义的物理化学条件下，AuH3SiO40的浓度远远高于AuCl2-,指出以硅络合对Au的活化迁移比氯重要得多。在含硫和硅的体系中，随着SiO2的增高，AuH3SiO40的作用将比Au（HS）2-更显重要。Au在SiO2水溶液中的溶解可表述为：SiO的沉淀是导致Au沉淀析出的有效机制，因此说明硅化与金矿化具有内在的联系。  相似文献   

Dissolution of hydrous Th （Ⅳ） oxide in aqueous Na^＋-H^＋-OH^——NO3^——H2O^- solutions in the presence of citrate, EDTA and oxalate     

Ziya S. Cetiner Scott A. Wood 《中国地球化学学报》2006,25(B08):245-246

Data on the hydrolysis of Th （Ⅳ） and solubility of ThO2 in the presence of organic ligands are of critical importance to the safe disposal and treatment of high-level nuclear waste. Such data are required to predict reliably thorium behaviour in high-level waste repositories where organic anions may be present. In addition, recent studies of the performance of thorium-based fuels report that these fuels can be used to reduce concerns related to potential proliferation of nuclear weapons and disposal of the current uranium dioxide fuel waste. Because several reactor concepts based on thorium fuel cycles are under consideration, it is important to have thermodynamic data to predict how such fuel and its waste form will behave in the environment. To establish the effect of pH and organic ligands on the hydrolysis of Th （Ⅳ）, experiments on the solubility of hydrous ThO2 in aqueous solution at room temperature were performed, covering a wide range of pH （pH=3.0 to 12.0） in 0.1 molal NaNO3 solutions. Experiments also were conducted in the presence of citrate, EDTA and oxalate with a concentration range 100 to 500 μmol. Approach to equilibrium was from supersaturation. Slopes of straight lines fit to plots of log mTh vs. pH were approximately -4 at the acidic region and near 0 at neutral and alkaline region for experiments conducted at constant ionic strength （I=0.1）, implying that the dominant Th species should be Th4^＋ and Th （OH）4（aq） The←→Th^4＋＋2H2O ThO2＋2H2O←→Th （OH）40 as follows： ThO2＋4H^＋ solubility of ThO2 decreases with increasing pH （pH 3 -6） and remains near the detection limit of ICP-MS （in the order of 10^-9 M to 10^1- M） in the range of pH 6-12. These values are in accordance with data in the literature.  相似文献   

A Preliminary Study of the Solubility of Copper in Water Vapor at Elevated Temperatures and Pressures     

尚林波  胡瑞忠  樊文苓 《中国地质大学学报(英文版)》2006,17(1):84-88

INTRODUCTIONAs early as 1644 , Ren啨Descartes proposed thatsilver-,gold-,and lead-bearing veins were producedby the condensation of vapors emanating from theearth' s interior ( Williams-Jones et al ., 2002) . Butthe solubility of many metals is higher in liquid thanin vapor andtherefore the focus of research on hydro-thermal ore deposits was placed on hydrothermal sys-tems (Barnes ,1997) ,considering the fact that ore-forming elements may exist as complexes in hydro-thermal solutions . T…  相似文献   

Mercury mobilization by oxidative dissolution of cinnabar (α-HgS) and metacinnabar (β-HgS)     

Elizabeth A. Holley  A. James McQuillan  Dave Craw  Jonathan P. Kim  Sylvia G. Sander 《Chemical Geology》2007,240(3-4):313-325

Cinnabar (α-HgS) and metacinnabar (β-HgS) dissolved at environmentally significant rates in oxygenated slurry experiments simulating a low-flow fluvial system. Based on SO₄²⁻ production, cinnabar dissolution rates were 2.64 to 6.16 μmol (SO₄²⁻) m^− 2 day^− 1, and metacinnabar dissolution rates were 1.20 to 1.90 μmol (SO₄²⁻) m^− 2 day^− 1. Monodentate-bound thiosulfate (S₂O₃²⁻) was identified as an oxidation product on the HgS surface by ATR-IR spectroscopy based on strong infrared absorption bands in the 1140–1145 cm^− 1 and 1006–1014 cm^− 1 regions. The presence of sulfide oxidation intermediates on the HgS surface indicates that SO₄²⁻ concentration underestimates α-HgS and β-HgS dissolution in this setting. Mercury release rates during dissolution were more than two orders of magnitude less than SO₄²⁻ production, but were significant: 0.47 mg (Hg) m^− 2 y^− 1 from cinnabar [6.45 nmol (Hg) m^− 2 day^− 1], and 0.17 mg (Hg) m^− 2 y^− 1 from metacinnabar [2.29 nmol (Hg) m^− 2 day^− 1]. The Hg mobilized during α-HgS and β-HgS dissolution is sufficient to form natural Au–Hg amalgam in downstream placer settings. The proportion of mercury that is not remobilized during α-HgS and β-HgS dissolution likely adsorbs to the dissolving mercuric sulfide. Adsorption of Hg²⁺ to cinnabar was detected in situ by anodic stripping voltammetry using a cinnabar-modified carbon paste electrode following accumulation of Hg²⁺ on the electrode at open circuit potential.  相似文献   

岩浆中磷灰石溶解度的研究进展     

叶立金  翟双猛 《矿物学报》2015,35(2):178-184

磷灰石在岩浆中的溶解行为有助于理解熔体的演化、微量元素如REE、U、Th、Sr等的分异和地幔交代流体的形成。本文综述了硅酸盐熔体中温度、熔体成分(Si O2、Ca O、Al2O3、S等)和碳酸盐熔体中温度、Ca O含量等对磷灰石溶解度的影响,介绍了已建立的溶解度模型以及采用模型成功解释实际成岩成矿过程的例子。在概述研究进展的基础上,指出了压力、卤素和高压流体等对磷灰石溶解行为影响的研究的不足。  相似文献   

海面二氧化碳通量的动力学分析     

张淮  吴克俭  楼顺里 《中国海洋大学学报(自然科学版)》1996,(4)

探讨海气间二氧化碳的气体交换。指出海面气体交换的物理过程与大气的强迫作用有关。动力学分析表明：交换速度主要依赖于溶解度、摩擦速度和阻碍系数；海面通量则决定于海与气的浓度差和交换速度，而交换速度随风速增加而增大，随温度增大而减小，其模拟值与风洞实验值基本一致。根据１９９３年１０月、１９９４年４月和１０月在东海三个航次的测定和计算表明，东海海面的二氧化碳通量指向下，其平均值为－４５．５μｇ·ｍ－２ｈ－１  相似文献   

Dynamics analysis for flux of carbon dioxide across seasurface   总被引：1，自引：0，他引：1  

Zhang Huai  Sun Fu 《海洋学报(英文版)》1996,15(4):447-455

Ｄｙｎａｍｉｃｓ　ａｎａｌｙｓｉｓ　ｆｏｒ　ｆｌｕｘ　ｏｆ　ｃａｒｂｏｎ　ｄｉｏｘｉｄｅ　ａｃｒｏｓｓ　ｓｅａｓｕｒｆａｃｅＺｈａｎｇＨｕａｉａｎｄＳｕｎＦｕＡｂｓｔｒａｃｔ：ＴｈｅＣＯ２ｅｘｃｈａｎｇｅｂｅｔｗｅｅｎａｔｍｏｓｐｈｅｒｅａｎｄｓｅａ...  相似文献