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1.
The density of artificial seawater has been measured with a magnetic float densitometer at 1 atm. from 0 to 40°C (in 5° intervals) and from 0 to 21‰ chlorinity. The densities at each temperature have been fitted to a modified Root (1933) equation, and an equation based on the Debye-Hückel limiting law, where AV′, BV′, AV, BV and CV are temperature-dependent constants (related to the ion-water and ion-ion interactions of the major components), d0 is the density of pure water and ClV is the volume chlorinity — . The densities fit these equations to ±9 p.p.m. from 0 to 25°C and ±18 p.p.m. from 30 to 40°C. The densities for artificial seawater are in good agreement with our measurements of Copenhagen seawater and the results for natural seawater obtained from Knudsen's tables.The expansibilities of the artificial seawater mixtures have been calculated from the temperature dependence of the densities. The resulting expansibilities at each temperature were fitted to the equations and where AE′, BE′, AE, BE and CE are constants (related to the effect of temperature on the ion-water and ion-ion interactions of the major components) and α0 is the expansibility of pure water. The expansibilities fit these equations to ±1 p.p.m. and at 35‰ S agree within ±1 p.p.m. with the expansibilities obtained for natural seawater from Knudsen's tables.Theoretical density and expansibility constants have been determined from the apparent equivalent volumes and expansibilities of the major components of seawater by using the additivity principle. The average deviations of the calculated densities and expansibilities are, respectively, ±20 and ±3 p.p.m. over the entire temperature range. 相似文献
2.
J.V. Leyendekkers 《Marine Chemistry》1974,2(2):89-110
A general equation is derived for predicting the partial molal volume (pmv) of an electrolyte in seawater, using binary solution data, and seawater density data. The composition of seawater need not be “average” - prediction can be made for any composition. Simpler equations are derived for “average” seawater. The ranges cover , t = 0–30°C and p = 1–1,000 bar, subject to the availability of binary solution data. Estimates of the pmv's of a number of electrolytes are made and compared with experimental values and the summed ionic values. 相似文献
3.
Gypsum solubility in mixtures of Dead Sea and Mediterranean Sea waters at different ratios and in their concentrates obtained by evaporation simulation have been calculated using the Pitzer model as formulated by Harvie and Weare (1980). The results obtained are compared with available experimental gypsum solubility data in different natural brines, sea water, sea water concentrates and NaCl solutions. The agreement between theoretically calculated and experimental solubility values is fairly good and is within the range of scatter of the individual solubility measurements. 相似文献
4.
The ratio is at least a factor of two higher in the particulate phases of California coastal waters than the values previously reported for unfiltered waters and sediments. These results are attributed to a greater water solubility for plutonium relative to americium species. The values of the ratio in mussels indicate primarily a particulate uptake of these transuranics. Sorption experiments of these two elements from seawater to glass beads, rayon fibres and filter papers are consistent with an uptake of the particulate phases. 相似文献
5.
The densities (p) of artificial solutions of Dead Sea waters have been measured at 20°, 25°, 30°, 35° and 40°C using a vibrating tube densimeter. The resulting relative densities (p — po, where po is the density of water) have been used to determine an equation of state for Dead Sea waters. The average deviation between experimental values and those calculated from the obtained equation was 0.000020 g ml?1. A thermal expansion coefficient and the coefficients characterizing the influence of the changes in salt or ionic concentrations on the density of Dead Sea waters were calculated, and they were shown to be temperature and concentration dependent. The densities of Dead Sea waters were found to be very sensitive to any changes in ionic composition. The partial molal volumes of salt components were calculated and discussed. 相似文献
6.
《Deep Sea Research Part I: Oceanographic Research Papers》1999,46(10):1779-1792
Many of the deep basins filled by hot brines in the Red Sea have not been investigated since their discovery in the early 1970s. Twenty years later, in September 1992, six of these deeps were revisited. The temperature and salinity of the Suakin, Port Sudan, Chain B, and Nereus deeps ranged from 23.25 to 44.60°C and from 144 to 270‰. These values were approximately the same in 1972, indicating that the budget of heat and salt was quite balanced. We measured strong gradients of properties in the transition zone between brines and overlying seawater. The contribution of salinity to the density gradient was more than one order of magnitude higher than the opposite contribution of temperature across the seawater–brine interface. Therefore the interface was extemely stable, and the transfer of properties across it was considered to be controlled mostly by molecular diffusion. We calculate that the diffusional transport of salt from the brines to seawater cannot affect significantly the salinity of the brines over a 20 year period, which agrees with the observations. The brine pools can persist for centuries with no salt input. Therefore, the persisence of brines does not correspond to a steady balance between diffusional loss and continuous input of hydrothermal solutions. Deeps that experience only episodical hydrothermal brine supplies may persist for a long time with salt inherited from past inputs. The theoretical loss of heat by diffusion from the brine to seawater was higher than the observed decrease in temperature of the brine pool during the 20 year period of observation. We calculated that the heat flux out of the pools into the overlying seawater was compensated by a heat flux into the pools of about 250–600 mW/m2. This range of values corresponds to bottom heat flow values that have been reported earlier for the axial zone of the Red Sea. In contrast to the other brine pools, the temperature and salinity of the Valdivia Deep brine increased by 4.1°C and 10‰, respectively, between 1972 and 1992, which is explained by present-day hydrothermal brine discharge. 相似文献
7.
Boris S. Krumgalz 《Marine Chemistry》1989,27(3-4)
The solubilities of halite in Dead Sea waters and in their mixtures with Mediterranean Sea waters were estimated using Pitzer's equations. The calculated halite saturation for Dead Sea waters sampled at various occasions during 1979–1983 is in good agreement with the naturally observed phenomenon of halite deposition at this time. A halite saturation curve for mixtures of Dead Sea and Mediterranean Sea waters has been obtained and permits the prediction of halite deposition in these mixtures on evaporation. 相似文献
8.
The Tait-Gibson parameter, , and the refractive index of seawater are estimated from binary solution data. The predicted and experimental values agree closely. The maximum deviations, at , are 1.7 bars for and 0.0001 for the refractive index. The results show that binary solution data, analysed on the basis of the Tammann-Tait-Gibson model for aqueous solutions, can be used to predict the properties of seawater of composition different to that of standard seawater. 相似文献
9.
《Deep Sea Research Part I: Oceanographic Research Papers》2000,47(8):1583-1590
Over the next 5–10 years, the WOCE hydrographic program will generate reliable hydrographic data for the world oceans. The resultant conductivity salinity, temperature, and pressure data will generate calculated densities that will be used to examine mixing along constant density surfaces. Changes in the composition of deep waters due to the breakdown of plant material can effect the calculated densities at a given conductivity salinity. The increases in SiO2, nitrate, alkalinity, and TCO2 (or pH) can change the density of seawater as well as the conductivity. For studies of the salinity and density fields over small spatial scales, these changes will be small, but for large scale and ocean to ocean studies the differences can be significant. The density calculations based on the salinity determined from conductivity need to be adjusted for the offsets due to changes in the composition of seawater. This report describes how this correction should be made using existing information. 相似文献
10.
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
11.
The various assumptions implicit in the calculation of acid dissociation constants (based on ionic medium standard states) from potentiometric titrations using a cell with liquid junction (i.e. a pH measuring cell) have been examined. It was concluded that results can be obtained having an accuracy commensurate with the experimental precision. It has been shown that although the precise composition of the medium is a function of the hydrogen ion concentration (because of the protolytic nature of some of the ions in the media, e.g., sulphate and fluoride), the effect of such variations in the medium composition can be compensated for when defining the activity of hydrogen ion on an ionic medium standard state by defining the concentration of hydrogen ion as: where βHSO4 and βHF are the relevant association constants and ST and FT are the total concentrations of sulphate and fluoride, respectively.This approach was used to obtain values for the ionic product of water (KW) in artificial seawater media at various temperatures and ionic strengths. These were fitted to give the equation (molal concentration units): where I is the formal ionic strength of the artificial seawater medium and T is the absolute temperature. The values obtained are in reasonable agreement with those found by previous workers. 相似文献
12.
Velocity and suspension measurements in the logarithmic layer of hydraulically smooth turbulent tidal flow from the North Sea are reported. The data were not compatible with the assumption of Newtonian flow for the experimental seawater—clay suspension.Laboratory measurements were initiated with mud and seawater from the North Sea in which the boundary-layer structure of this two-phase flow was measured down into the viscous sublayer. The dilute seawater—clay suspension was a mixture of illite, kaolinite and chlorite minerals with concentrations less than 380 mg/l and exhibited turbulent drag reduction.By reviewing flow measurements of other authors it is suggested that turbulent drag reduction occurs on a geophysical scale if the flows transport cohesive sediments. It is proposed that drag reduction is caused by dynamic interaction between turbulent shear strain in the flow and deformation of aggregates.As a consequence, the values of the critical friction velocity and of erosion rates must be reviewed for cohesive bottom materials. Normally they were obtained under the assumption of a Newtonian flow structure which is not applicable if the flow transports cohesive sediments.To detect the occurrence of drag reduction in geophysical boundary layers (hydraulically smooth), flow measurements must be performed down into the viscous sublayer. The adequate velocity sensors must have a diameter of ?1 mm. 相似文献
13.
14.
Seventy-nine δ13C analyses of oceanic particulate matter (> 0·μ) from semi-tropical (Gulf of Mexico, Caribbean and Atlantic) and polar (South Indian Ocean) waters showed that the carbon isotope composition of the particulate matter from the cold polar surface waters was lighter () than that from the surface in the semi-tropical regions (), reflecting the temperature effect on the photosynthetic fixation of carbon. δ13C for deep samples (> 330 m) were generally more negative than the surface samples, except in some well-mixed polar areas.A difference both in organic carbon isotopic composition and percentage organic carbon in the POM and the tops of sediment cores was also apparent; a loss of approximately 95 % of incoming carbon and an increase in 13C of several per mille being observed during deposition of particulate matter. This indicates that after settling on the bottom there is extensive diagenesis of the POM by organisms, indicating the non-refractory nature of the organic matter. 相似文献
15.
Recent data on world average river water composition and global mean composition of crustal rocks have allowed a reconsideration of earlier work on the concept of a chemical steady-state in the world ocean system. In the light of these new data, initial statistical analyses have been reinterpreted or modified. This paper reports improved correlations between mean oceanic residence times () and water—rock partition coefficients (KY), and between KY and the electronegativity function (QYO). Such correlations support the concept that the average composition of seawater can be estimated, based on a simple dynamic model, using the electronegativities of elements and the rate of input of dissolved components. 相似文献
16.
Bulk composition of ferromanganese nodules from the pelagic environment of the Pacific Ocean is apparently related to nodule-growth rate, sediment-accumulation rate, and biologic productivity in the overlying seawater. Nodules with a high ratio and high Ni and Cu concentrations tend to occur in areas where primary productivity in the surface layer of the ocean is high and the sediment-accumulation rate low. Nodules with a low ratio and low Ni and Cu concentrations occur in areas either where sediment-accumulation rate is high or biologic productivity is low. They may have a ratio as low as one and accrete at rates as low as . Nodules with a larger ratio apparently have growth rates that are greater by as much as a factor of 10. 相似文献
17.
Victor W. Truesdale 《Marine Chemistry》1975,3(2):111-119
An iodine component in seawater, which is ‘unreactive’ to the total inorganic method described by Truesdale and Spencer (1974), has been discovered. The component is measured as the increase in ‘reactive’ iodine that accompanies irradiation of seawater with high-intensity UV light. The highest concentration recorded for an inshore water was . As some known organic-iodine compounds behave in a similar manner to UV irradiation, it is suggested that the ‘unreactive’ iodine is organically bound iodine. 相似文献
18.
《Deep Sea Research Part II: Topical Studies in Oceanography》2010,57(16):1460-1477
We targeted the warm, subsurface waters of the Eastern Mediterranean Sea (EMS) to investigate processes that are linked to the chemical composition and cycling of dissolved organic carbon (DOC) in seawater. The apparent respiration of semi-labile DOC accounted for 27 ± 18% of oxygen consumption in EMS mesopelagic and bathypelagic waters; this value is higher than that observed in the bathypelagic open ocean, so the chemical signals that accompany remineralization of DOC may thus be more pronounced in this region. Ultrafiltered dissolved organic matter (UDOM) collected from four deep basins at depths ranging from 2 to 4350 m exhibited bulk chemical (1H-NMR) and molecular level (amino acid and monosaccharide) abundances, composition, and spatial distribution that were similar to previous reports, except for a sample collected in the deep waters of the N. Aegean Sea that had been isolated for over a decade. The amino acid component of UDOM was tightly correlated with apparent oxygen utilization and prokaryotic activity, indicating its relationship with remineralization processes that occur over a large range of timescales. Principal component analyses of relative mole percentages of monomers revealed that oxygen consumption and prokaryotic activity were correlated with variability in amino acid distributions but not well correlated with monosaccharide distributions. Taken together, this study elucidates key relationships between the chemical composition of DOM and heterotrophic metabolism. 相似文献
19.
Spectrophotometric measurements are reported for the first apparent dissociation constant of hydrogen sulfide in seawater over the temperature range 7.5–25°C and 2–35.8‰ salinity. These data are described by the expression . The second apparent dissociation constant in potassium chloride solution was estimated potentiometrically using a sulfide specific ion electrode. A value of ～13.6 was found for pK2′ at a KCl concentration of 0.67 M. It is suggested that explicit reference to the sulfide ion, S2?, in describing equilibria in marine waters be dropped in favor of a formulation involving the bisulfide ion, HS?. 相似文献