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1.
The densities of artificial and real Red Sea brines have been measured at 25°C with a vibrating tube densimeter. Measurements were also made on mixtures of Red Sea brines with seawater and pure water. The results have been used to characterize the density—composition relations of waters across the interface of brine and average Red Sea waters. The results for the real and artificial brines are in reasonable agreement.The composition of the brines and mixtures with seawater have been characterized by conductivity measurements of weight diluted samples. The conductivity salinities were found to be conservative to within for the mixtures.The densities of brines and mixtures of brines and seawater were estimated from apparent molal volume data using Young's rule. The calculated densities for all of the solutions were found to be in good agreement with the measured values, demonstrating the applicability of Young's rule to concentrated natural waters. 相似文献
2.
《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(10):1999-2008
Elevated methane (CH4) concentrations (128–2692×103 nM) occur in the hypersaline anoxic brine pools of Bannock and Urania Basins, eastern Mediterranean Sea, compared to low concentrations (17–80×103 nM) in the sediments below the anoxic brines. The CH4 enrichment in the brines might be due to the long residence time of the brine in the Basin. An attempt is made to determine the sources for the enriched dissolved CH4 by considering the influence of hydrothermal activity, the occurrence of sapropel layers (biogenic) and dissolution of gas hydrates. Furthermore, it is suggested that the enriched CH4 in Bannock and Urania Basins is diffused and mixed with the overlying waters by local upward transport mechanisms that selectively move CH4 upward in these Basins. 相似文献
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The distribution and speciation of iodine, a biophilic redox-sensitive trace element, in waters overlying and in the Orca Basin, Gulf of Mexico, which contains hypersaline, anoxic and yet non-sulfide-bearing brine have been determined. The distribution of iodate and iodide in the oxic waters overlying the anoxic brine are similar to those reported in other oceans. However, in the oxic-anoxic mixing zone, iodate disappears while the concentration of iodide reaches a maximum of 8.1 μM, the highest concentration ever reported in open oceans. There is also a maximum in specific iodine of 30.7 nM‰?1 at this depth. Specific iodine in oxic seawater is only about 10–14 nM ‰?1. These features may be explained by the preferential dissolution of biogenic particles that have accumulated in a strong pycnocline. In the anoxic brine proper, the concentration of iodide is 3.8 μM and can be explained almost entirely by the simultaneous mobilization of chloride and iodide during the dissolution of evaporite beds as the specific iodine of 14.5 nM‰?1 is only slightly higher than those observed in the oxic waters. 相似文献
5.
The stability of gypsum in marine sediments using the entire ODP/IODP porewater composition database
The stability of gypsum in marine sediments has been investigated through the calculation of its saturation index at the sediment in situ temperature and pressure, using the entire ODP/IODP porewater composition database (14416 samples recovered from sediments collected during 95 ODP and IODP Legs). Saturation is reached in sediment porewaters of 26 boreholes drilled at 23 different sites, during 12 ODP/IODP Legs. As ocean bottom seawater is largely undersaturated with respect to gypsum, the porewater Ca content or its SO4 concentration, or both, must increase in order to reach equilibrium. At several sites equilibrium is reached either through the presence of evaporitic gypsum layers found in the sedimentary sequence, and/or through a salinity increase due to the presence of evaporitic brines with high concentrations of Ca and SO4. Saturation can also be reached in porewaters of seawater-like salinity (≈ 35‰), provided sulfate reduction is limited. In this case, saturation is due to the alteration of volcanogenic material which releases large amounts of Ca to the porewaters, where the Ca concentration can reach 55 times its seawater value as for example at ODP Leg 134 site 833. At a few sites, saturation is reached in hydrothermal environments, or as a consequence of the alteration of the basaltic basement. In addition to the well known influence of brines on the formation of gypsum, these results indicate that the alteration of sediments rich in volcanogenic material is a major process leading to gypsum saturation in marine sediment porewaters. Therefore, the presence of gypsum in ancient and recent marine sediments should not be systematically interpreted as due to hypersaline waters, especially if volcanogenic material is present. 相似文献
6.
Victor Quintino Ana Maria Rodrigues Rosa Freitas Ana R 《Estuarine, Coastal and Shelf Science》2008,79(3):525-532
Most of the studies on biological and ecological effects associated with brine discharge into the marine environment are related to the operation of desalination plants, for the production of freshwater. In this study we analysed the biological effects of a brine effluent from a completely different source, produced from the lixiviation of rock salt caves, for the creation of natural gas storage caverns. Lethal and sub-lethal endpoints following exposure to the brine were studied in a range of macrofauna species characteristic of the soft and hard bottom habitats in the vicinity of the discharge area, namely the isopod Eurydice pulchra, the annelids Sabellaria alveolata and Ophelia radiata, the sea-urchin Paracentrotus lividus and the bivalve Mytilus galloprovincialis. In a first series of experiments, brine, with salinity above 300, was diluted in distilled water to a salinity value close to that of the seawater in the discharge area (salinity 36) and, surprisingly, none of the exposed species was able to survive or develop into viable larvae. A second series of experiments exposed the species to brine diluted with seawater, simulating more realistic discharge circumstances. All the tested species at all the measured endpoints (adult survival, larval abnormal development, sperm fertilization success) showed negative biological effects in brine solutes always at a lower salinity than that of a salinity control obtained with concentrated seawater. The sub-lethal experiments with larval development of P. lividus, S. alveolata and M. galloprovincialis, and the fertilization success of P. lividus gave EC50 values for the brine solute with salinity in the range of 40.9–43.5, whereas the EC50 values for the concentrated seawater were in the range of salinity 44.2–49.0. It is hypothesised that differences in the ionic composition of the brine cause the inability of the species to tolerate the exposure to brine. 相似文献
7.
Sulphate-related equilibria in the hypersaline brines of the Tyro and Bannock Basins, eastern Mediterranean 总被引：1，自引：0，他引：1
G.J De Lange N.A.I.M Boelrijk G Catalano C Corselli G.P Klinkhammer J.J Middelburg D.W Müller W.J Ullman P Van Gaans J.R.W Woittiez 《Marine Chemistry》1990,31(1-3)
The Tyro and Bannock Basins, which are depressions in the eastern Mediterranean, contain hypersaline anoxic brines. These brines are of different composition: Tyro brine is primarily an early-stage halite (NaCl) brine, whereas Bannock brine includes the more soluble ions of late-stage evaporite minerals. Accordingly, the Bannock brine contains a much greater sulphate concentration than the Tyro Brine. This difference in sulphate concentration is reflected in the concentrations of ions such as Ca, Sr and Ba, which form sparingly soluble sulphate minerals.Equilibrium calculations using the Pitzer specific ion interaction model indicate that the brines in both basins are saturated with respect to gypsum (CaSO4-2H2O) and supersaturated to saturated with respect to dolomite (CaMg(CO3)2). The degree of saturation with respect to dolomite is greater in the Bannock Basin than it is in the Tyro Basin. Correspondingly, recent gypsum crystals and dolomite hardgrounds have been found in the Bannock Basin but not in the Tyro Basin.The Tyro brine is homogeneous in composition, whereas the Bannock brine demonstrates a clear two-layer brine structure. At the interface of the upper and the lower brine distinct positive anomalies occur in the total alkalinity and the concentration of phosphate, and negative anomalies occur in the concentrations of Mn2+ and the rare earth elements (REE). These anomalies and the observed association of gypsum/dolomite in the sediments are all consistent with a recent precipitation of dolomite and gypsum in the Bannock Basin. The brines in both basins are also saturated with respect to barite (BaSO4).The 87Sr/86Sr and δ34S ratios of the Bannock brines are amazingly consistent but differ dramatically from the values for modern or Messinian-age seawater. The Sr concentration and Sr and S isotope ratios in the gypsum crystals indicate that most of these crystals have resulted from precipitation/recrystallization from the brine and not from seawater. The observed variations between crystals are thought to reflect the recrystallization of (sub-) outcropping Messinian gypsum with a low 87Sr/86Sr ratio in the presence of seawater or brine fluids and with different extents of diagenesis. 相似文献
8.
J. Acosta E. Uchupi A. Muñoz P. Herranz C. Palomo M. Ballesteros 《Marine Geophysical Researches》2003,24(1-2):41-57
Circular to elliptical mounds in the Canary Channel with reliefs of 75 to 375 m and diameters of 4 to 8 km partially surrounded by moats with reliefs of 25 to 75 m, were formed by piercement of the seafloor by Mesozoic evaporites. Several long gullies, < 1km wide, with abrupt terminations and pockmarks associated with these mounds were probably eroded by dense brine and hydrocarbon seeps. The salt brines that eroded the gullies were formed where salt diapirs intersect the seafloor, or in the subsurface by circulating ground water heated by igneous activity along the Canary Ridge. If the brines originated in the subsurface they reached the seafloor along faults. Displacement of the surficial sediments by sliding and creep is probably the result of the expulsion of hydrocarbons and/or vertical motion of the Mesozoic evaporites. Microtopographic features along or near the east flank of the Canary Ridge are the creation of uplift of the ridge, hydrothermal activity, mass wasting processes and turbidity currents. 相似文献
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The activity of NaCl in artificial seawater was measured potentiometrically with Na+- and Cl? -sensitive electrodes. The salinity of the solutions, examined at 25°C, ranged from 10–40‰ salinity. The change in the activity from 5–25°C was measured at 35‰ salinity.The molal mean activity coefficient of NaCl in 35‰ seawater at 25°C is 0.667. The relative partial molal enthalpy of NaCl in 35‰ seawater is ?130 ±50 cal mol?1. This value is in good agreement with the value measured in pure 0.72 M NaCl.The results were compared with activity coefficients predicted by a specific interaction model and by an ion association model. Good agreement was found in both cases. 相似文献
11.
水下量子密钥分配对保障水下通信安全具有十分重要的意义。本文研究不同温度或盐度的海水对光传输以及水下量子密钥分配的影响。本文在有限的范围内改变水槽中水的温度或盐度,在温盐均匀和有温盐差的海水信道中对出射光进行偏振测试,并进行了基于偏振编码的BB84协议水下量子密钥分配实验研究。研究表明:偏振光经过温盐均匀或有温盐差的模拟海水后其偏振态几乎不发生变化;在温盐均匀的海水中,温度或盐度的变化几乎不改变误码率,但在温盐不均匀的海水中,误码率随温盐差的增大呈增加趋势。 相似文献
12.
Catherine Pierre Germain Bayon Marie-Madeleine Blanc-Valleron Jean Mascle Stéphanie Dupré 《Geo-Marine Letters》2014,34(2-3):253-267
On the passive margin of the Nile deep-sea fan, the active Cheops mud volcano (MV; ca. 1,500 m diameter, ~20–30 m above seafloor, 3,010–3,020 m water depth) comprises a crater lake with hot (up to ca. 42 °C) methane-rich muddy brines in places overflowing down the MV flanks. During the Medeco2 cruise in fall 2007, ROV dives enabled detailed sampling of the brine fluid, bottom lake sediments at ca. 450 m lake depth, sub-surface sediments from the MV flanks, and carbonate crusts at the MV foot. Based on mineralogical, elemental and stable isotope analyses, this study aims at exploring the origin of the brine fluid and the key biogeochemical processes controlling the formation of these deep-sea authigenic carbonates. In addition to their patchy occurrence in crusts outcropping at the seafloor, authigenic carbonates occur as small concretions disseminated within sub-seafloor sediments, as well as in the bottom sediments and muddy brine of the crater lake. Aragonite and Mg-calcite dominate in the carbonate crusts and in sub-seafloor concretions at the MV foot, whereas Mg-calcite, dolomite and ankerite dominate in the muddy brine lake and in sub-seafloor concretions near the crater rim. The carbonate crusts and sub-seafloor concretions at the MV foot precipitated in isotopic equilibrium with bottom seawater temperature; their low δ13C values (–42.6 to –24.5‰) indicate that anaerobic oxidation of methane was the main driver of carbonate precipitation. By contrast, carbonates from the muddy lake brine, bottom lake concretions and crater rim concretions display much higher δ13C (up to –5.2‰) and low δ18O values (down to –2.8‰); this is consistent with their formation in warm fluids of deep origin characterized by 13C-rich CO2 and, as confirmed by independent evidence, slightly higher heavy rare earth element signatures, the main driver of carbonate precipitation being methanogenesis. Moreover, the benthic activity within the seafloor sediment enhances aerobic oxidation of methane and of sulphide that promotes carbonate dissolution and gypsum precipitation. These findings imply that the coupling of carbon and sulphur microbial reactions represents the major link for the transfer of elements and for carbon isotope fractionation between fluids and authigenic minerals. A new challenge awaiting future studies in cold seep environments is to expand this work to oxidized and reduced sulphur authigenic minerals. 相似文献
13.
有关太平洋海洋环流,特别是对亚热带(又称副热带)、热带和赤道带环流的调查研究,近数十年来在国内、外海洋学界已蓬勃展开。其中,日本气象厅于1967年至今在137°E断面上每年进行1-2次定期海洋观测,并于1972-1979年、1987-1995年在155°E断面上每年夏季进行一次观测。根据上述经向断面观测资料,许多学者对137°E断面的海流结构,温、盐分布,水团及其变异,以及与ENSO现象的关系作了细致的分析研究(邹娥梅等,1993;顾玉荷,1996;Guan,1986;Masuzawa,1967);关于155°E断面的研究,则着重于太平洋赤道区域海流结构和它的变异及其与ENSO现象的关系等(顾玉荷,1990;Guan,1986)。本文拟根据155°E断面1972-1979年夏季(6-7月)日本气象厅的海洋水文气象观测资料(其中1974年无资料),分析研究该断面(北亚热带、热带和赤道带海域)的温、盐度分布特征和热、盐含量及其年际变异,并探讨其与ENSO现象之间的关系。
155°E断面北起30°N,南至11°S,自北向南横穿北亚热带、热带、赤道带和南半球热带。测站的密度以1975-1977年最密(设55个测站),1972年和1973年次之(分别设测站33个和40个),1978年和1979年测站稀疏,仅为15个和12个。采样深度间隔于30m以浅为10m,50-150m层间为25m,150-300m层间为50m,300-1000m层间为100m。图1为断面的位置和站位分布(5028站至5058站每相邻两站中间省略一站位)。
为了便于分析断面上各纬度带的水文特征及年际变异,将该断面自北向南划分为4个纬度带,即北亚热带(18°-30°N)、北半球热带(2°-18°N,以下简称北热带)、赤道带(2°N-2°S)和南半球热带(2°S以南,以下简称南热带)。其中北热带又划分为北赤道流区(8°-18°N)和北赤道逆流区(2°-8°N)。 相似文献
14.
Various investigators reported a decrease in pH as seawater is concentrated. A similar phenomenon was reported for Dead Sea waters which are about ten times more saline than seawater. The reasons for the low pH values of Dead Sea waters (pH 5.9–6.5), which precipitate CaCO3, were investigated by determining the apparent dissociation constants of carbonic acid in these brines. A new method, based on alkalinity titration and least-squares fitting, was used to estimate the proton activity coefficient (γH+) and the first and second dissociation constants of carbonic acid (K1′, K2′) in natural and artificial Dead Sea waters. It was found that as the salt content increases, pK′1 and pK′2 values progressively decrease whereas γH+ sharply increase. At the highest salinity investigated (TDS = 330 gl?1) γH+ pK′1 and pK′2 values are 24.5, 5.09 and 6.23, respectively, as compared to about 0.8, 5.9, 9.1 respectively for normal seawater (19‰ chlorinity) at the same temperature (30°C).The implication of the results of this study regarding solubility of CaCO3 and the general behavior of the carbonate system in hypersaline solutions is discussed. 相似文献
15.
J.V Leyendekkers 《Marine Chemistry》1980,9(1):25-35
Equations are given for estimating the heat capacity of binary and multicomponent electrolyte solutions on the basis of the TTG model. These equations are used to calculate the heat capacity of seawater solutions up to a concentration of 45‰ for the temperature range 0–30°C and up to a concentration of 160‰ at 20°C. The deviations from the experimental values are less than the uncertainties due to smoothing and experimental errors. The results suggest that the heat capacity of other multicomponent solutions, including non-standard seawater solutions, could be predicted to within 0.1% or better, up to an ionic strength of about 3 M. 相似文献
16.
Seawater Intrusion in Semi-Closed Convergent Estuaries (Case Study of Moroccan Atlantic Estuaries): Application of Salinity Analytical Models 总被引：1，自引：0，他引：1
Salinity is an important parameter influencing the water quality of estuaries, and can constitute a serious problem to society due to the need for freshwater for industry and agriculture. Therefore, the determination of salt intrusion length in estuaries is a challenge for managers as well as scientists in this field. The managers tend to use simple and reliable tools for salinity variation. Although 2-D and 3-D numerical models are common tools for the prediction of salinity intrusion now, analytical models of salinity variation are much more efficient, and also require minimal sets of river data. In this paper, two analytical solutions, Brockway and Savenije used worldwide to assess longitudinal salinity variation in alluvial estuaries, are applied to the Moroccan Atlantic semi-closed estuaries, i.e., Sebou and Loukkos. The solutions are derived from salt convection-dispersion equations, with different assumptions for the dispersion coefficient. The estuaries' bathymetry is described by an exponential function. The performance of these two solutions was evaluated by comparing their results with field-measured salinity data. The Brockway model's salinity predictions performs well to observations especially in downstream reaches of the two estuaries (Sebou: R2 = 0.95, root mean square error [RMSE] = 1.50‰, normalized root mean square error [NRMSE] = 3.45‰; Loukkos: R2 = 0.95, RMSE = 1.13‰, NRMSE = 3.01‰), while the Savenije model outperformed the Brockway's model and is better to predict salt intrusion length and salinity variation along the two estuaries (Sebou: R2 = 0.97, RMSE = 1.15‰, NRMSE = 2.85‰; Loukkos: R2 = 0.98, RMSE = 0.95‰, NRMSE = 1.94‰). This revealed that both analytical solutions apply well to the estimation of salinity variation and the prediction of salt intrusion in these two estuaries. 相似文献
17.
M. f. Fitzsimons P. R. Dando J. A. Hughes F. Thiermann I. Akoumianaki S. M. Pratt 《Marine Chemistry》1997,57(3-4)
A shallow hydrothermal brine seep located off the Greek island of Milos in the Aegean Sea was studied. The brine fluid outcropped as a pool of water in a seabed depression and was detected in the surrounding pore-waters of sediments colonised by the sulphur bacterium Achromatium volutans. The seep fluid was highly saline and sulphidic, depleted in Mg2+ and SO42−, but enriched over seawater in Na+, Ca2+, K+, Cl−, SiO2, reduced species and dissolved gases. The high concentrations of Na+, Ca2+ and K+ were consistent with the Milos tectonic setting. Na-K and Na-K-Ca geothermometers predicted a reservoir temperature of 300–325 °C for the most concentrated seep samples. The deep geothermal reservoir within the metamorphic basement of Milos island has already been located and studied and may represent the source of the seep fluid. Faunal diversity was lowest in seep-influenced sediments, but a sulphide-intolerant species was found in areas of the bacterial mat where salinity and temperature were much lower. Pressure-induced variations in the vertical depth of the brine interface may be occurring in the sediment. 相似文献
18.
Growth rates of two halophilic phytoflagellates, Dunaliella euchlora Lerche and D. salina Teodoresco, were studied in mixed batch cultures grown in filtered, axenic brines from Lake Grassmere, New Zealand. Forty‐five combinations of temperature, salinity, and light intensity were used. A maximum growth rate of 1.50 doublings day‐1 was attained by D. salina at 26°C, 190 × 10‐3S at a light intensity of 126 μE m‐2 s‐1. D. euchlora showed maximum growth rate of 1.16 doublings day‐1 at 20°C, 120 × 10‐3S at a light intensity of 180 μE m‐2s‐1. Predicted maximum values of 1.41 and 1.14 doublings day‐1 respectively were obtained from regression models based on 45 replicate treatment combinations. In decreasing order of importance, temperature, salinity, and light intensity influence growth rates of brine algae. The optimum temperature for growth of both species increased as the salt concentration increased but decreased with increasing light intensity. 相似文献
19.
莱州湾南岸平原地下水化学特征研究 总被引：2，自引：0，他引：2
用2009年莱州湾南岸地下水最新监测数据,将研究区地下水淡水区、微咸水区、咸盐水区和卤水区进行经典统计分析、相关分析、等值线图和Piper三线图绘制,阐述了水化学类型和成分特征从南往北的变化:EC、TDS、Na+、K+、Mg2+、Cl-、SO42-的平均浓度从南部淡水到北部卤水呈现逐渐增大趋势,因为在卤水区普遍发生碳酸钙沉淀,Ca2+和HCO3-则在咸盐水区浓度达最高;pH值从淡水到卤水呈现从弱碱性到弱酸性的转变;从淡水区向卤水区地下水化学组分阴离子由HCO3-为主变为Cl-为主,阳离子由Ca2+为主变为Na+为主;此外河流对地下水起到淡化和冲刷的作用。主成分分析法提取了水化学3个主成分,分别代表了地下水盐化指标、生物化学作用和碳酸钙沉淀。进一步结合系数比值法和饱和指数计算,在对本区水文、地质以及离子水文地球化学特性分析基础上,指出地下卤水阴阳离子中占绝对优势的Cl-、SO42-、Na+、Mg2+的毫克当量百分数与正常海水的值非常相近而与地下淡水的值相差甚远,反映出本区地下卤水起源于古海水,为沉积海水。此外卤水绝非海水简单浓缩的产物,其间还包括复杂的水化学变质过程及后期演化如矿物沉淀、阳离子交换(K+-Ca2+;Na+-Ca2)+、去白云岩化作用和硅酸盐蚀变等。饱和指数的计算表明石膏在卤水矿化度达100 g/L之后才开始缓慢沉淀,而文石、方解石和白云石基本一直处于饱和沉淀状态,且文石和方解石的饱和指数散点分布极为相似,说明两者可能同时发生沉淀。 相似文献
20.
Oceanology - Barium sulfate solubility in diluted Na2SO4–NaNO3 solutions and seawater of 35‰ salinity at 22°C was studied in experiments. The value obtained for the thermodynamic... 相似文献