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1.
Thermal decomposition, temperatures of four organic Zn complexes were evaluated experimentally by determining the change in sphalerite solubility with temperature in aqueous solutions containing organic compounds. The results show that decomposition takes place at 180°±5°C for lactic acid-Zn complex, 200°±5°C for EDTA-Zn, 240°±5°C for quinone-Zn and 190°±5°C for fulvic acid-Zn. It is also shown that at 190°–200°C sphalerite solubility is 4 to 7 times higher in NaCl solution containing organic compounds than that in NaCl solution without organic compounds. Studies were also conducted on the contents of Pb and Zn complexed by fulvic acid and humic acid in aqueous solutions the infrared spectra of fulvic acid-Zn and humic acid-Zn complexes, the differential thermal analysis of fulvic acid, humic acid and quinone and EDTA, and the variation in fulvic acid solubility in the seawater with temperature.  相似文献   

2.
深层、超深层中有机酸的分布特征及其热稳定性对储层物性有着重要影响。采用高温高压水—岩模拟装置对储层中典型一元和二元有机酸（乙酸和乙二酸）的分解反应进行了模拟,对动力学参数进行了计算,并分析其影响因素。结果显示:乙二酸比乙酸更容易分解,且分解反应的速率更高;乙酸和乙二酸分解反应的起始温度分别为230 ℃和180 ℃,其反应速率随着温度的升高而急剧增加。反应体系中高pH值和钾长石的存在明显提高了乙酸和乙二酸分解反应的反应速率,但对起始温度影响较小。高流体压力和静岩压力均会抑制乙酸和乙二酸的分解,在提高有机酸分解反应起始温度的同时降低分解反应速率。从地质意义上来讲,相对高压、低地温的地层环境更有利于有机酸的保存,因此具有低地温梯度的沉积盆地形成深层—超深层优质储层的可能性更高。  相似文献   

3.
Analysis of experimental data reported by Lagache (1965, 1976), Evans (1965), Busenberg (1975), Busenberg and Clemency (1976), Holdren and Berner (1979), Siegel and Pfannkuch (1984), and Chou and Wollast (1984) with the aid of irreversible thermodynamics and transition state theory (Aagaard and Helgeson, 1977, 1982) suggests that at temperatures at least up to 650°C, the rate of both congruent and incongruent feldspar hydrolysis in aqueous solutions far from equilibrium at pH ? 10.6 ? (2300/T), where T stands for temperature in kelvins, is a function solely of effective surface area and pH at constant pressure and temperature. At higher pH, the rate is apparently pH-independent up to ~pH 8 at 25°C, where it again becomes pH-dependent at higher pH. Observations of scanning electron micrographs indicate that the cross-sectional area of etch pits on hydrolyzed feldspar grains is of the order of 10?9 to 10?8 cm2 and that the ratio of the effective to total surface area (which may or may not change with reaction progress) ranges from <0.01 to 1, depending on the grain size, dislocation density, and the extent of comminution damage on the surfaces of the grains. Apparent rate constants retrieved from experimental data reported in the literature for feldspar hydrolysis in the lower pH-dependent range extend from ~10?13 to ~10?7 moles cm?2 sec?1 at temperatures from 25° to 200°C, which is consistent with activation enthalpies for albite and adularia of the order of 20 kcal mole?1. In contrast, the apparent rate constants for the pH-independent rate law range from ~10?16 to ~10?11 moles cm?2 sec?1 at temperatures from 25° to 650°C, which requires an activation enthalpy for adularia of ~ 9 kcal mole?1. These observations are consistent with surface control of reaction rates among minerals and aqueous solutions. The rate-limiting step in the pH-dependent case apparently corresponds at the lower end of the pH scale to breakdown of a protonated configuration of atoms on the surface of the reactant feldspar, but at higher pH the rate is limited by decomposition of an activated surface complex corresponding in stoichiometry to hydrous feldspar. In highly alkaline solutions, an activated complex containing hydroxyl ions apparently controls the rate of feldspar hydrolysis. Nevertheless, near equilibrium, regardless of pH the rate is proportional to the chemical affinity of the overall hydrolysis reaction.  相似文献   

4.
A large number of aqueous metal complexes contribute significantly to hydrothermal, metamorphic, and magmatic processes in the crust of the Earth. Nevertheless, relatively few thermodynamic data other than dissociation constants (K) for a few dozen of these complexes have been determined experimentally at elevated temperatures and pressures. The calculations summarized below are intended to supplement these experimental data by providing interim predictions of the thermodynamic properties of supercritical aqueous metal complexes using the revised HKF (Helgeson et al., 1981) equations of state for aqueous species (Tanger and Helgeson, 1988; Shock et al., 1992) and correlations among equations of state parameters and standard partial molal properties at 25 degrees C and 1 bar (Shock and Helgeson, 1988, 1990; Shock et al., 1989). These equations and correlations permit retrieval of the conventional standard partial molal entropies (mean S0), volumes (mean V0), and heat capacities (mean C0P) of aqueous metal complexes at 25 degrees C and 1 bar from published values of log K in the supercritical region and the limited number of experimental dissociation constants available in the literature over relatively short ranges of elevated temperature at PSAT (PSAT and SAT are used in the present communication to refer to pressures corresponding to liquid-vapor equilibrium for the system H2O except at temperatures <100 degrees C, where they refer to the reference pressure of 1 bar). The standard partial molal properties computed in this way can then be used to generate corresponding values of delta mean S0, delta mean V0, and delta mean C0P of association, which for similar complexes correlate linearly with mean S0, mean V0 and mean C0P, respectively, of the constituent cations and ligands at 25 degrees C and 1 bar. Generalizing these correlations and combining them with the equations of state permits prediction of the temperature and pressure dependence of log K and other thermodynamic properties of a large number of aqueous metal complexes. As a consequence, it is possible to retrieve values of log K at 25 degrees C and 1 bar from the results of hydrothermal experiments at higher temperatures and pressures or to predict values of log K at hydrothermal conditions when no experimental data are available at temperatures and pressures above 25 degrees C and 1 bar. Such predictions can be made for temperatures and pressures from 0 degrees C and 1 bar to 1000 degrees C and 5000 bars.  相似文献   

5.
The dipeptide isoleucyl-glycine in aqueous solution has activation energies for isoleucine epimerization and hydrolysis of 23.1 and 20.9 kcal mol?1, respectively. The activation energy for epimerization of NH2-terminal isoleucine is 5–8 kcal mol?1 less than activation energies reported for epimerization of isoleucine in the free state or in various protein systems. Furthermore, the rate of isoleucine epimerization in the NH2-terminal position exceeds the rate of hydrolysis at temperatures between 0 and 152°C. Consequently, a high rate of epimerization in fossils should only occur when isoleucine is in the terminal position. Partially epimerized isoleucine will be converted through hydrolysis from the terminal form to the slower epimerizing free isoleucine. Over the course of the total isoleucine epimerization reaction, either in dipeptides or proteins, the activation energy will increase and the reaction rate will decrease as terminal isoleucine is converted to free isoleucine. This process may explain the non-linear kinetics observed for isoleucine epimerization in carbonate fossils.The degree of isoleucine epimerization is low in different molecular weight fractions of a fossil protein from Mercenaria in all fractions greater than 500 mol. wt, where most isoleucine is likely to be in the interior position. In the less than 500 mol. wt peptide fraction, where a considerable portion of the isoleucine is likely to be in the terminal position, the degree of epimerization is significantly greater. These analytical results from fossil protein support the interpretation of isoleucine kinetics obtained by study of dipeptides.  相似文献   

6.
Results are reported of long-term pressure-solution experiments that were initiated by the late E.M. Duyvis.A sample consisting mainly of quartz sand was compacted under a load2 which was increased at a rate of 6.7 atm/day up to a maximum of 710 atm, during which a temperature of 340°C and a pore pressure of 160 atm were maintained.Thin sections cut from the compacted sample were compared with similar sections from natural quartz sands. The interior of the laboratory sample showed a distinct similarity with pressolved sand found in a Venezuelan Tertiary sandstone buried at 4000 m (Lake Maracaibo, Block III). At the edges of the laboratory sample we observed in some places amorphous silica instead of quartz overgrowth. The formation of this unstable mineral indicates that a high supersaturation must have existed in the pores. The inhibition of the quartz formation in these places is possibly due to the presence of iron contamination originating from the steel pressure cell.To investigate the influence of temperature on the compaction process, a series of experiments were carried out in which pure quartz samples were subjected to loading at lower temperatures than above, the load being increased at a rate of 7 atm/day up to a maximum of 500 atm. These experiments revealed that when samples have undergone some consolidation the presence of water is essential for continuation of the compaction process.The results of the compaction tests emphasize the importance of the pressure-solution process, which markedly influences both compaction rate and formation strength and thus the porosity of the formation.  相似文献   

7.
The Martabe Au–Ag deposit, North Sumatra Province, Indonesia, is a high sulfidation epithermal deposit, which is hosted by Neogene sandstone, siltstone, volcanic breccia, and andesite to basaltic andesite of Angkola Formation. The deposit consists of six ore bodies that occurred as silicified massive ore (enargite–luzonite–pyrite–tetrahedrite–tellurides), quartz veins (tetrahedrite–galena–sphalerite–chalcopyrite), banded sulfide veins (pyrite–tetrahedrite–sphalerite–galena) and cavity filling. All ore bodies are controlled by N–S and NW–SE trending faults. The Barani and Horas ore bodies are located in the southeast of the Purnama ore body. Fluid inclusion microthermometry, and alunite‐pyrite and barite‐pyrite pairs sulfur isotopic geothermometry show slightly different formation temperatures among the ore bodies. Formation temperature and salinity of fluid inclusions of the Purnama ore body range from 200 to 260 C and from 6 to 8 wt.% NaCl equivalent, respectively. Formation temperature and salinity of fluid inclusions of the Barani ore body range from 200 to 220 °C and from 0 to 2.5 wt.% NaCl equivalent and those of the Horas ore body range from 240 to 275 °C and from 2 to 3 wt.% NaCl equivalent, respectively. The Barani and Horas ore bodies are less silicified and sulfides are less abundant than the Purnama ore body. A relationship between enthalpy and chloride content indicates mixing of hot saline fluids with cooler dilute fluids during the mineralization of each of the ore bodies. The δ18O values of quartz samples from the southeast ore bodies exhibit a wide range from +4.2 to +12.9‰ with an average value of +7.0‰. The δ18O values of H2O estimated from δ18O values of quartz, barite and calcite confirm the oxygen isotopic shift to near meteoric water trend, which support the incorporation of meteoric water. Salinity of the fluid inclusions decrease from >5 wt.% NaCl equivalent in the Purnama ore body to <3 wt.% NaCl equivalent in the Barani ore body, indicating different fluid systems during mineralization. The δ34S values of sulfide and sulfate in Purnama range from ? 4.2 to +5.5‰ and from +1.2 to +26.7‰, those in the Barani range from ? 4.3 to +26.4‰ and from +3.9 to +18.5‰ and those in the Horas ore body range from ? 11.8 to +3.5‰ and from +1.4 to +25.7‰, respectively. The δ34S of total bulk sulfur in southeastern ore bodies (Σδ34S) was estimated to be approximately +6‰. The estimated sulfur fugacity during formation of the Purnama and Horas ore bodies is relatively high. It was between 10?4.8 and 10?10.8 atm at 220 to 260 °C. Tellurium fugacity was between 10?7.8 and 10?9.5 atm at 260 °C and between 10?9 and 10?10.6 atm at 220 °C in the Purnama ore body. The Barani ore body was formed at lower fS2, lower than about 10?14 atm at 200 to 220 °C based on the presence of arsenopyrite and pyrrhotite in the early stage, and between 10?14 and 10?12 atm based on the existence of enargite and tennantite in the last stage. © 2016 The Society of Resource Geology  相似文献   

8.
A method of extraction for amino acids from soils and sediments involving superheated water has been investigated. About 75–97 per cent of the amino acids contained in four soils of a soil profile from Illinois were extracted by this method. Deep penetration of water into soil aggregates and partial hydrolysis of peptide bonds during this extraction by water at high temperature are likely mechanisms responsible for the release of amino acids from samples. This extraction method does not require subsequent desalting treatments when analyses are carried out with an ion-exchange amino acid analyzer.  相似文献   

9.
This study reports the kinetic experimental results of albite in water and in KCI solution at 22 MPa in the temperature range of 25 to 400℃. Kinetic experiments have been carried out in an open flow-through reaction system (packed bed reactor). Albite dissolution is always incongruent in water at most temperatures, but becomes congruent at 300℃ (close to the critical point 374℃). At temperatures from 25 to 300℃, the incongruent dissolution of albite is reflected by the fact that sodium and aluminum are easily dissolved into water; from 300 to 400℃ it is reflected by silicon being more easily dissolved in water than Al and Na. Maximum albite dissolution rates in the flow hydrothermal systems have been repeatedly observed at 300℃, independent of flow rates.The kinetic experiments of albite dissolution in a KCl aqueous solution (0.1 mol KCl) indicate that the dissolution rate of albite increases with increasing temperature. Maximum silicon release rates of albite have been observed at 400℃, while ma  相似文献   

10.
刘金钟  傅家谟 《地质科学》1993,28(3):246-253
用实验方法研究了含原油水溶液、油田卤水、腐植酸、脂肪酸、氨基酸及无水体系中原油对金的络合及迁移作用。结果表明,原油、腐植酸对金有很强的络合能力,水溶液中含少量的原油即可大大提高水溶液对岩石中金的淋滤活化能力。沉积地层成岩过程中产生的低熟有机质可能是促进沉积改造型金矿床矿源层中金活化迁移的重要因素。  相似文献   

11.
Determination of alloThr/Thr ratios in foraminiferal tests ranging in age from Recent to ～ 700,000 yr B.P. has shown that threonine epimerization ratios approach a steady-state value of ～0.2. This is well below the equilibrium ratio of ～0.9 as measured in buffered aqueous solutions. It has also been found that the initial rate of decomposition of threonine in fossil foraminfera is about an order of magnitude faster than would be predicted on the basis of extrapolation from high temperature kinetic studies on free threonine in buffered aqueous solution. These results are apparently a consequence of metal cation catalysis of both the decomposition and the epimerization of free threonine, which is being continually released by the slow hydrolysis of peptide and proteinaceous material present in the fossil shells.  相似文献   

12.
Deuterium-enriched amino acids occur in the Murchison carbonaceous chrondrite. This meteorite underwent a period of aqueous alteration with isotopically light water. With the objective of setting limits on the conditions of aqueous alteration, the exchange of the carbon-bonded hydrogen atoms of amino acids with D2O has been studied from 295 to 380 K as a function of time and meteorite/heavy water ratio. The amount of Murchison or Allende dust present has a significant effect on the rate and amount of hydrogen-deuterium exchange observed. At elevated temperatures, the alpha-hydrogens of all the amino acids studied were found to exchange with deuterium. In glycine and aspartic acid, this process resulted in total exchange of the carbon-bonded hydrogen. A completely deuterated isotopomer of alanine was produced in significant quantities only when the rock/water ratio was greater than 0.5. No exchange of carbon-bonded hydrogens was observed in the case of amino acids which do not possess an alpha-hydrogen atom. The rates of H/D exchange for amino acids observed here did not correspond to deuterium enrichment of the amino acids in the Murchison meteorite. These results suggest that H/D exchange with water had a negligible effect on the observed deuterium enrichment of amino acids found in Murchison and that the temperature at which the amino acids were exposed to liquid water was close to 273 K.  相似文献   

13.
Experiments were carried out on the thermal decomposition of sporopollenin, isolated from a marine algae (Lycopodium clavatum) at constant temperature (380°C) and pressure (around 200 atm), but for varying pyrolysis times.The decomposition products were separated into groups, analysed by chromatography and infra-red spectroscopy, and their elemental composition determined. The thermal evolution of sporopollenin proceeds in three distinct steps: first, a partial decomposition of the initial substance occurs with the formation of soluble materials. This is followed by a full decomposition of the sporopollenin and disappearance of the non-soluble residue. Finally, a non-soluble material reappears. It is proposed that, due to secondary reactions, the evolution of kerogen of the sapropelic type is similar to what has been observed in mild pyrolysis experiments.  相似文献   

14.
CH4-H2O体系流体包裹体均一过程激光拉曼光谱定量分析   总被引：6，自引：2，他引：4  
对南黄海盆地二叠纪地层中某石英脉中的CH4-H2O体系流体包裹体均一过程进行了激光拉曼光谱定量分析。利用甲烷与水的拉曼峰面积比值计算不同温度下流体包裹体中水溶液相中甲烷的浓度,除了在100℃附近出现最小值,随温度增加甲烷浓度呈指数增大。包裹体在214℃完全均一,均一时甲烷的浓度为0·1347mol/L。同时利用甲烷的拉曼特征对流体包裹体均一过程的内压变化作了分析。压力变化可以分为三个区间:19~100℃,随温度升高压力增大;100~150℃压力随温度升高减小;150℃之后压力迅速增大。均一温度下的内压为21·92MPa。流体包裹体内压的变化主要是由甲烷溶解行为和封闭体系的热力学特征决定的。实验表明激光拉曼光技术可以作为定量分析含甲烷流体包裹体的一种有效方法。  相似文献   

15.
Carbonate minerals and water （or geofluids） reactions are important for modeling of geochemical processes and have received considerable attention over the past decades. The calcite dissolution rates from 50℃ to 250℃ at 10 MPa in deionized water with a flow rate varying from 0.2 to 5 mL/min were experimentally measured in a continuous flow column pressure vessel reactor. The dissolution began near the equilibrium with c/ceq 〉 0.3 and finally reached the equilibrium at 100℃-250℃, so the corresponding solubility was also determined as 1.87, 2.02, 2.02 and 1.88×10^-4.mol/L at 100℃, 150℃, 200℃ and 250℃ respectively, which was first increasing and then switching to decreasing with temperature and the maximum value might occur between 150℃ and 200℃. The experimental dissolution rate not only increased with temperature, but also had a rapid increase between 150℃ and 200℃ at a constant flow rate of 4 mL/min. The measured dissolution rates can be described using rate equations of R = k（1-c/ceq）n or R = kc-n. In these equations the reaction order n changed with temperature, which indicates that n was a variable rather than a constant, and the activation energy was 13.4 kJ/mol calculated with R = k（1-c/ceq）n or 18.0 kJ/mol with R = kc^-n, which is a little lower than the surface controlled values. The varied reaction order and lower activation energy indicates that calcite dissolution in this study is a complex interplay of diffusion controlled and surface controlled processes.  相似文献   

16.
温度梯度、含水率梯度和压力梯度对非饱和土体中的水热迁移有重要影响。用非饱和黄土填筑室内模型,通入0.10MPa高温水蒸气,研究蒸汽压梯度、温度梯度和含水率梯度耦合作用下的水热迁移规律。结果表明:在水蒸气迁移范围之内,土体的升温速率、增湿速率和增湿程度较大,以蒸汽传热和压力梯度驱动的水蒸气增湿为主。而在水蒸气未到位置,以温度梯度引起的热传导和含水率梯度与温度梯度耦合驱动的水热迁移为主;水蒸气迁移时,受土颗粒阻碍和蒸汽压消散的影响,土体升温速率、增湿速率和温度传导速率均随径向距离的增大而减小,且增湿速率小于升温速率;水蒸气增湿土体的最大含水率接近最优含水率,增湿效果较好,可有效提高一定范围内土体的压实性能;基于模型试验边界条件,确定含湿毛细多孔介质中二维热湿迁移方程的一组代数显式特解,并以20 cm测点为例,将温度和含水率实测值和计算值进行对比分析。研究结果可为非饱和黄土水-汽-热耦合传输规律和水蒸气增湿新技术研究提供理论支持。  相似文献   

17.
Rates of anaerobic decomposition of Lake Erie sediments were determined for seven depth intervals at three temperatures. Sealed sediment sections were incubated under anoxic conditions and the interstitial waters were serially sampled over a period of approximately 200 days. Concentration increases of bicarbonate, phosphate, ammonium, Ca, Mg, Fe and Mn in pore water within any given depth interval followed zero order kinetics over the sampling period and exhibited Arrhenius temperature dependency. Rates of release to the pore waters were proportional to the concentrations in the solid phases, indicating first order kinetics overall.The rates and temperature dependencies of these fermentation reactions were only slightly less than those reported from sediments undergoing sulfate reduction. The observed release rates decreased exponentially with depth in the sediment due to a corresponding decrease in the amount of metabolizable organic matter and acid hydrolyzable mineral phases.A stoichiometric model was constructed utilizing the observed release rates and assumed chemical reactions to predict the stoichiometry of the decomposing organic matter and the nature of the hydrogen buffer. The modeling indicates that 60% of the observed bicarbonate release is the direct result of organic decomposition, that 20% of the release is from the dissolution of calcium carbonate mineral phases, and that the remaining 20% of the release is from the dissolution of magnesium, iron und manganese carbonate mineral phases.Kinetic modeling of the observed production rates accurately predicts the vertical profiles of Ca, Mg, Fe and Mn, but cannot quantitatively account for all the concentration differences of the nutrient elements C, N and P. This implies that in addition to decomposition, increased depositional flux also accounts for the significant changes in concentrations of the nutrient elements in the near surface sediments.  相似文献   

18.
Feldspar group minerals reacting with water at depth determine, by their reaction with environment, the character of newly formed minerals. Although plagioclase is the most abundant member of this group experimental data are very limited on the nature of its reactions under high pressure and temperature conditions. The author experimented on acid plagioclase with analytical data and physical constants corresponding to those of oligoclase. The reaction between oligoclase and water was studied under various pressures and temperatures, using a diffusion autoclave (previously described by the author [1]). Silicon, sodium, and aluminum in significant amounts went into solution; and, smaller amounts of calcium and potassium were observed. With increased temperature, larger amounts of material constituting oligoclase went into solution: The maximum occurred at 350 to 400° C; and, a marked decrease, at 500 to 600° C. Quantitative ratios of material in the condensate were found to correspond to albite indices. Increased pressure does not alter this behavior, there is only increased passage of separate components of the mineral into solution. At 350°, newly formed material was not observed microscopically; at higher temperatures, kaolinite and chalcedony appeared at sucessively higher temperatures. Experimentation by Morey and Chen on albite indicate that transfer of the albite component of oligoclase into solution is predominant. By comparison of its stability with that of two other minerals, albite is the most reactive with water. At 350° Centigrade and under pressure of 350 kilograms per square centimeter, the transfer into solution (in milligrams per liter) is for albite, 318; for microcline, 268; and, for oligoclase, 220. Labradorite was studied under analogous conditions; in that the transfer of labradorite predominates over that of the anorthite molecule, its behavior corresponds to albite. It was found that basic plagioclase shows less stability than is evident from microscopic examination of plagioclase in rocks. Data from these and previous experiments indicate possible types of solutions that can form within intragranular spaces in rocks by reaction between acid plagioclase and water. It is evident from the data that leaching of the albite component predominates by variation in composition of the solution throughout a wide range of temperature and pressure conditions. --D. D.Fisher  相似文献   

19.
A commercial (Setaram C80) calorimeter has been modified to measure the heat capacities of highly caustic solutions at temperatures up to 300 °C and pressures up to 20 MPa. The improvements have allowed more accurate determination of the isobaric volumetric heat capacities of chemically aggressive liquids at high temperatures. Test measurements with aqueous solutions of sodium chloride showed a reproducibility of about ±0.1%, with an accuracy of ∼0.3% or better, over the whole temperature range. Heat capacities of aqueous solutions of sodium hydroxide at concentrations from 0.5 to 8 mol/kg were measured at temperatures from 50 to 300 °C and a pressure of 10 MPa. Apparent molar isobaric heat capacities of NaOH(aq) were calculated using densities determined previously for the same solutions by vibrating-tube densimetry. Standard state (infinite dilution) partial molar isobaric heat capacities of NaOH(aq) were obtained by extrapolation using an extended Redlich-Meyer equation. Values of the standard heat capacity change for the ionization of water up to 300 °C were derived by combining the present results with the literature data for HCl(aq) and NaCl(aq).  相似文献   

20.
The relationships between electrical conductivity, temperature, salinity, and density are studied for brackish Lake Issyk-Kul. These studies are based on a newly determined major ion composition, which for the open lake shows a mean absolute salinity of 6.06 g kg−1. The conductivity-temperature relationship of the lake water was determined experimentally showing that the lake water is about 1.25 times less conductive than seawater diluted to the same absolute salinity as that of the lake water. Based on these results, an algorithm is presented to calculate salinity from in-situ conductivity measurements. Applied to the field data, this shows small but important vertical salinity variations in the lake with a salinity maximum at 200 m and a freshening of the surface water with increasing proximity to the shores. The algorithm we adopt to calculate density agrees well with earlier measurements and shows that at 20°C and 1 atm Lake Issyk-Kul water is about 530 g m−3 denser than seawater at the same salinity. The temperature of maximum density at 1 atm is about 0.15°C lower than that for seawater diluted to the same salinity. Despite its small variations, salinity plays an important role, together with temperature changes, in the static stability and in the production of deep-water in this lake. Changes in salinity may have had important consequences on the mixing regime and the fate of inflowing river water over geological time. Uncharged silicic acid is negligible for the stability of the water column except near an ∼15 m thick nepheloid layer observed at the bottom of the deep basin.  相似文献   

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