Major Constituents Of Seawater Research Articles

Influence of Individual Ions on Silica Nanoparticles Interaction with Berea Sandstone Minerals

Nanofluids are prepared by dispersing silica nanoparticles in aqueous media (brines). The purpose of this work is to address brine/rock interactions in presence of nanoparticles. Our previous studies have shown that silica nanofluids are effective in reducing formation damage in sandstone reservoirs. This study addresses effect of individual ions on dispersed silica nanoparticles’ interaction with Berea Sandstone minerals. The selected ions are Mg2+, SO42− and Na+, in MgCl2, Na2SO4 and NaCl, which are the major constituents of seawater. Three flooding stages for Berea Sandstone cores were followed. The first flooding stage was without nanoparticles, the second one was a slug of the nanoparticles with tracer and the third stage was a post-flushing of the core with the respective ion. The effluent tracer concentration, nanoparticle content, ion concentrations and pH reflect the effect of individual ions on nanoparticle/mineral interaction which were used for suggesting possible interaction mechanisms. Presence of Mg2+ and SO42− ions improved the adsorption of nanoparticles on minerals, however the effect of Na+ was lesser. In general, in all the cases nanoparticles reduced the mineral dissolution and associated fine migration/possible formation damage.

Aerosol time-series measurements over the tropical Northeast Atlantic Ocean: Dust sources, elemental composition and mineralogy

The North Atlantic receives the largest dust loading of any of the world's oceans due to its proximity to North African deserts and prevailing wind patterns. The supply of biologically important trace elements and nutrients via aerosols has an important influence on biogeochemical processes and ecosystems in this ocean region. In this study we continuously sampled aerosols between July 2007 and July 2008 at the Cape Verde Atmospheric Observatory (CVAO), which is situated on an island group close to the North African continent and under the Saharan/Sahelian dust outflow path. The aim of our work was to investigate temporal variations in aerosol concentration, composition and sources in the Cape Verde region over a complete seasonal cycle, and for this purpose we undertook mineralogical and chemical (42 elements) analyses of the aerosol samples and air mass back-trajectory calculations. Aerosol samples were also collected during a research cruise in the (sub-) tropical Northeast Atlantic Ocean in January 2008.The concentration of atmospheric Al, a proxy for mineral aerosol concentration, at CVAO was in the range of 0.01–66.9μgm−3 (maximum on 28–30 January 2008) with a geometric mean of 0.76μgm−3. It showed distinct seasonal variations, with enhanced Al concentrations in winter (geometric mean 1.3μgm−3), and lower concentrations in summer (geometric mean 0.48μgm−3). These observations have been attributed to dust transport occurring in higher altitude air layers and mainly north of the Cape Verde during summer, while in winter the dust transport shifts south and occurs in the lower altitude trade winds with consequent greater influence on the Cape Verde region. The elemental composition of the aerosols closely agreed with mean upper crustal abundances, with the exception of elements with pronounced anthropogenic sources (e.g. Zn and Pb) and major constituents of sea water (Na and Mg). Mineral analysis showed that clays were the most abundant mineral fraction throughout the whole sampling period, with an increase in quartz and clays during strong dust events and an associated decrease in calcite. This could have important implications for the estimation of release of for example Fe from mineral dust with clays having a higher Fe solubility than quartz.The elemental composition and mineralogy of aerosol samples collected during the cruise were indistinguishable from those collected at the CVAO during the same period, although mean atmospheric Al was 65% higher at the CVAO than those measured on the ship due to the irregular and uneven nature of dust transport.Air mass back-trajectories showed an important role for southern source regions of the North African deserts during summer, with 92.5% of the samples indicating a contribution from the Sahel. Significantly elevated ratios of V, Ni, Cu, Zn, Cd and Pb with Al were present in samples originating from the Sahel compared with samples with a more northerly origin. This was likely due to enhanced anthropogenic emissions related to the greater population densities in the Sahel compared with the less developed Saharan regions further north.Ratios of other elements and trends in rare earth elements could however not be used to distinguish differences in source regions. Similar source material compositions, the mixing of dust from different regions during transport, and the pooling of samples over a 1–3day collection period appear to have diluted specific signals from source regions.

Seawater Ca2+ concentration influences solar orientation inTalitrus saltator(Crustacea, Amphipoda)

The role of salinity in the ecophysiology of many intertidal invertebrates has been extensively investigated. Calcium (Ca(2+)), magnesium (Mg(2+)), potassium (K(+)) and sodium (Na(+)) are the major constituents of seawater and it has been demonstrated that sandhoppers tested under the sun in diluted seawater (3.5 per thousand) head seaward, instead of going landward as expected. Therefore, the variation in seawater salinity (from 35 per thousand to 3.5 per thousand) influences their directional choice. This paper investigates the contribution of different cations to the sea-land directional choice of Talitrus saltator (Crustacea, Amphipoda) by the sun compass orientation mechanism. Results of releases carried out in basic seawater selectively deprived of Ca(2+), Mg(2+) or K(+) and containing the same concentration of Na(+) indicate that only the reduction in Ca(2+) concentration affects the capacity of solar orientation. The pH does not influence the directional choice of sandhoppers and nor do small variations in salinity in the range 32-39 per thousand. Moreover, the clear photopositive tendency registered in experiments of phototaxis in Ca(2+)-deprived seawater indicates that the absence of Ca(2+) does not affect the normal functioning of the visual cells. Therefore, our results show that Ca(2+) seawater concentration is important for the correct functioning of one of the principal mechanisms of orientation in supralittoral amphipods and it could affect their survival in the field.

98/04238 Protection of the environment and rational use of wastes and byproducts from coking

A number of short-term laboratory experiments have been carried out, using radiotracers and artificial and natural seawater solutions, to examine the possible variables which could influence the behaviour of neptunium in seawater. Parameters considered include initial oxidation state, sorption by suspended particulate material and chemical composition of the solution phase.Results indicate that the uptakes of Np(IV) and Np(V) species by suspended sediment exhibit different kinetics. For Np(IV), rapid initial sorption was observed followed by desorption over longer time periods. In contrast, initial sorption of Np(V) was followed by further uptake of the species, but at a slower rate. No evidence was obtained to suggest that Np(V) is reduced to Np(IV). Although a large proportion of Np(IV) was rapidly oxidised to Np(V) under neutral and alkaline pH conditions, the rate of conversion slowed progressively with time. Only a small, but nevertheless measurable, amount of dissolved Np(IV) remained after equilibrating for 24 h. In addition, the kinetics of Np(IV) oxidation and Th(IV) sorption were remarkably similar in seawater containing a relatively small amount of particulate material. Although it has been shown that the major constituents of seawater can influence Np(IV) sorption and oxidation kinetics, to a first approximation, a consistent redox equilibrium was attained within a relatively short period (24 h). Laboratory data are discussed in the context of extrapolating trends to natural systems and, environmental observations of the behaviour of 237Np discharged into the Irish Sea from the BNFL nuclear fuels reprocessing plant at Sellafield (U.K.).

Equilibrium studies in natural fluids: interactions of -PO43−, -P2O74− and -P3O105− with the major constituents of sea water

The interaction of PiO(i+2)−(3i+1) (i = 1,2,3) with the major components of seawater has been studied potentiometrically, at 25°C, in an artificial seawater (Na+, K, Ca2+, Mg2+, Cl− and SO42−) at different salinities (5—45%o). Apparent protonation constants have been calculated, from potentiometric data, and estimated, using an appropriate complex formation model. Formation constants of complexes formed by phosphates and the cation of seawater (the inorganic content of seawater being considered as a single 1:1 salt) have been determined. The comparison between experimental and estimated results showed that a suitable complexation model can be used with a fairly good accuracy in predicting acid–base properties of polyphosphates in seawater. The single salt approximation for the inorganic major components of seawater, which is a good tool in estimating the mean strength of polyanion interaction in seawater, has been applied.

Laboratory studies to investigate short-term oxidation and sorption behaviour of neptunium in artificial and natural seawater solutions

Abstract A number of short-term laboratory experiments have been carried out, using radiotracers and artificial and natural seawater solutions, to examine the possible variables which could influence the behaviour of neptunium in seawater. Parameters considered include initial oxidation state, sorption by suspended particulate material and chemical composition of the solution phase. Results indicate that the uptakes of Np(IV) and Np(V) species by suspended sediment exhibit different kinetics. For Np(IV), rapid initial sorption was observed followed by desorption over longer time periods. In contrast, initial sorption of Np(V) was followed by further uptake of the species, but at a slower rate. No evidence was obtained to suggest that Np(V) is reduced to Np(IV). Although a large proportion of Np(IV) was rapidly oxidised to Np(V) under neutral and alkaline pH conditions, the rate of conversion slowed progressively with time. Only a small, but nevertheless measurable, amount of dissolved Np(IV) remained after equilibrating for 24 h. In addition, the kinetics of Np(IV) oxidation and Th(IV) sorption were remarkably similar in seawater containing a relatively small amount of particulate material. Although it has been shown that the major constituents of seawater can influence Np(IV) sorption and oxidation kinetics, to a first approximation, a consistent redox equilibrium was attained within a relatively short period (24 h). Laboratory data are discussed in the context of extrapolating trends to natural systems and, environmental observations of the behaviour of 237Np discharged into the Irish Sea from the BNFL nuclear fuels reprocessing plant at Sellafield (U.K.).

Equilibrium studies in natural fluids: a chemical speciation model for the major constituents of sea water

The speciation of CI−, OH− and SO42- in synthetic sea water has been studied by Potentiometric measurements (pH-metric and ISE-Na methods) and by literature data analysis, using a well tested complex formation model. Stability constants, together with distribution of hypothesised species in synthetic sea water, as a function of temperature and salinity, are reported. The speciation model proposed in this work is discussed on the basis of chemical and statistical considerations. Comparison with some literature sea water models is given.

Solvent extraction-spectrophotometric determination of anionic surfactants in sea water

A solvent extraction-spectrophotometric determination of anionic surfactants in sea water using ethyl violet is described. The anionic surfactant sodium dodecylsulphate (SDS) reacts with ethyl violet to form an ion associate which can be extracted into toluene. Some of the chloride also forms an ion associate with ethyl violet and is extracted simultaneously with SDS into toluene. As sea water contains large amounts of sodium chloride (about 0.5 M), the blank is very large. To eliminate the chloride interference, the toluene extract is washed with distilled water. The concentration of the surfactant can be determined by measuring the absorbance of the organic phase at 612 nm after washing. The calibration graph is linear over the range 0–9.0 × 10–6M SDS (in toluene) and the apparent molar absorptivity is 9.6 × 10–4 l mol–1 cm–1. As the method is free from interferences from major constituents of sea water, it can be applied to the determination of anionic surfactants in sea water at levels up to 0.15 p.p.m.

Compaction and movement of interstitial water in bottom sediments of the Saguenay Fjord, Quebec, Canada

Eight sediment cores were collected along the length of the Saguenay Fjord and Baie des Ha! Ha!, Québec, Canada. Profiles of the sediment water contents were determined for each core. Porosities were fitted to an exponential relation with core depth. The relation was modified to account for variations in granulometry and in organic carbon contents of the sediments. Porosities were observed to be more sensitive to variations in organic content than to variations in granulometry, and grain sorting appeared more important than grain size. Grain-size distribution of the sediments is in agreement with a sedimentation model where most of the suspended load enters the fjord from the Saguenay River and is deposited downstream with the surface current. The coarse particles are mainly found close to the head of the fjord, whereas the fine particles are carried farther downstream. Surface porosities were observed to be proportional to the sedimentation fluxes obtained from the literature whereas the compaction showed an inverse relationship. The fractional decreases in porosity due to compaction along the fjord indicate some horizontal flow of the interstitial water at both ends of the sampled part of the fjord. An average vertical interstitial pore water flow of 0.4 cm yr −1 with respect to the surface horizon is estimated from the data. This is small compared with the diffusion of the major constituents of sea water through the sediment.

Stability of ion pairs from gypsum solubility degree of ion pair formation between the major constituents of seawater

The stability constants of the ion pairs NaSO 4 −, KSO 4 −, MgSO 4 −, CaSO 4, MgCl + and CaCl + were determined at 25°C and 0.7 M formal ionic strength, by measuring the solubility of gypsum (CaSO 4 · 2H 2O) in different media. The media used contained one or two of the following electrolytes: NaCl, KCl, MgCl 2, NaClO 4, Mg(ClO 4) 2, Na 2SO 4. Values for the stability constants are 1.22, 1.84, 12.3, 30.6, 0.48 and 1.20 M −1, respectively, and the solubility product for gypsum is 2.87 · 10 −4 M 2. The distribution of the main constituents of seawater was calculated using these results and the values of the carbonate and bicarbonate constants given by Dyrssen and Hansson (1972–1973). The solubility of gypsum in seawater as calculated and determined experimentally was 21.43 m M and 21.10 m M, respectively.

The geologic history of sea water—an attempt to solve the problem

Thermodynamics and kinetics are both important in the operation of the ocean-atmosphere system. The carbonate chemistry of the oceans can be treated in terms of perturbations of a well-defined equilibrium state. The equilibrium state for silicates in sea water is less well defined, and thermodynamic arguments are much less persuasive. Kinetics are of overwhelming importance in determining—among other parameters—the nitrate concentration of sea water and the pressure of oxygen and nitrogen in the atmosphere. It is likely that a similar mix of attainment and non-attainment of equilibrium prevailed during the entire history of the oceans, and that the sedimentary record must be interpreted accordingly. Marine evaporites are among the most helpful sediments in reconstructing the geologic history of sea water. The relative abundance of minerals in marine evaporites is a complex function of the history of the enclosing basins, but their sequence, and the absence of many minerals typical of non-marine evaporites set rather interesting limits on possible excursions of the composition of sea water since late Precambrian time. It is likely that the concentration of the major constituents of sea water has rarely, if ever, been more than twice or less than half their present concentration during the past 700 million years. The similarity of the mineralogy of sedimentary rocks during the past 3500 million years suggests that the chemistry of sea water has been highly conservative. However, the extensive bedded cherts of the Precambrian, and the frequently associated banded iron formations do indicate a real evolution of the ocean-atmosphere system. They are explained most readily in terms of a higher silica content in Precambrian sea water and a lower oxygen pressure in the atmosphere. Fossil fuel burning will probably introduce some ten times the present content of CO 2 into the atmosphere during the next two centuries. The effects of the additional CO 2 on climate and on the shallow marine biota are presently very difficult to predict. Other man-made chemicals are produced in much smaller quantities than CO 2. However a number of these are so toxic, that their integrated effects are potentially much more damaging than those of fossil fuel burning.

Flame photometric determination of potassium in sea water and marine organisms

A convenient flame photometric procedure for determining potassium in sea water and biological materials is described. Factors affecting the intensity of the spectral line emitted by potassium ions were studied. The major constituents of sea water showed no spectral interference on the potassium analysis. Chloride ions and sulphuric acid gave a negative radiation interference while sodium ions showed a positive effect. The “internal standard addition” procedure was used for eliminating the effect of these interfering constituents. An average potassium/chlorinity ratio of 0.538 was obtained for the Pacific coastal water with potassium concentration being expressed in mg-atom. The applicability of this procedure for the détermination of potassium in biological materials was also demonstrated.

The Velocity of Sound in Sea Water

In the sonar detection of underwater objects an accurate knowledge of the velocity of sound in sea water, and its variation with chemical composition and temperature, is desirable. Eight samples of Caribbean Sea water collected at various depths were studied with respect to sound velocity, density, and chemical composition. At both 20° and 30°C the velocities (determined with a 3-megacycle ultrasonic interferometer) were about 4 meters/second higher than the values in Kuwahara's tables, for which an accuracy of 3 meters/second is claimed. The salinities determined by chemical analysis agreed closely with those calculated from the densities; a slight increase of salinity with depth was noted. In another series of experiments, the sound velocity, density, and adiabatic compressibility were determined over a wide range of concentration for pure solutions of each of the seven salts which are the major constituents of sea water. It was found that the compressibility and sound velocity observed for sea water agree to 0.1 percent with the values obtained by linear summation of the effects of the individual salts, each taken at the proper concentration. Finally, removing over 90 percent of the dissolved air was found to increase the sound velocity only by about 0.5 meter/second (the order of magnitude of the experimental error) in sea water, as well as in distilled water.

U.S. National Academy of Sciences : Agassiz Medal

THE National Academy of Sciences presented the Alexander Agassiz Gold Medal and honorarium for 1948 to Dr. Thomas Gordon Thompson at the autumn meeting of the Academy held at the University of California, Berkeley, on November 15. Dr. Thompson, professor of chemistry and director of the oceanographic laboratories of the University of Washington at Seattle and Friday Harbor in the State of Washington, has long been a leader in investigations of the complex chemistry of the ocean, with special attention to the waters of the north-east Pacific, Puget Sound, the San Juan Archipelago and the Bering and Chukchi Seas. Under his inspiration and leadership, his associates and students have devised and developed effective methods and techniques for the isolation and the quantitative determination of many of the elements and their compounds which occur in minute concentrations in sea water. Examples of such are iron, lithium, silicon, manganese, aluminium, boron and radium, the fluorides, phosphates and silicates, the isotopes of the elements of water and the dissolved gases, and the ionic ratios of the major constituents of sea water in various parts of the ocean. In organising the oceanographic laboratories at Seattle and Friday Harbor, Dr. Thompson brought together specialists in the fundamental sciences associated with the various departments of a great university, and directed their attention and stimulated their interest in the many problems presented by oceanic phenomena. Dr. Thompson has been chairman of various international committees, particularly the committee of the International Association of Physical Oceanography, appointed for the purpose of establishing standard units and procedures for the promotion of studies of the chemistry of the ocean. Established by Sir John Murray in 1911, the Alexander Agassiz Gold Medal is awarded by the Academy "for original contribution in the science of oceanography to scientific men in any part of the world".

Chemical Studies of the Western Pacific Ocean. I. The Chemical Composition of the Oceanic Salt. Part 1

Abstract (1) The major constituents of sea water from the Western Pacific Ocean near Japan have been quantitatively determined. The analytical results are as follows: the difference in the compositions between the world’s average and the Western Pacific is very small, except that the values of sodium and potassium are a little lower, while those of chloride and magnesium are but slightly higher, in the latter than in the former. (2) It is quite noteworthy that there is an astonishing agreement between the analytical results of the west and the northeast side of the Pacific Ocean. (3) A new indicator has been used for the determination of chlorinity; that is a mixed solution of fluorescein and starch. The superiority of this indicator has been briefly discussed. In conclusion, the author wishes to express his hearty thanks to Prof. T. Okada, Director of the Central Meteorological Observatory of Japan, for his kind guidance and the permission of publishing this report. He is also indebted to Mr. H. Matui for his earnest assistance throughout this work.