Major Components Of Seawater Research Articles

Chemical speciation of organic matter in natural waters. Interaction of nucleotide 5’ mono-, di- and triphosphates with major components of seawater

The interactions of nucleotide 5’ mono-, di- and triphosphates in a multicomponent ionic medium simulating the macro-composition of seawater (Na+, K+, Ca2+, Mg2+, Cl-, SO42-, Synthetic Sea Water, SSW) have been investigated at different ionic strengths and at T= 25°C. A chemical speciation model, according to which all the internal interactions between the components of the ionic medium are taken into account, was applied to determine the effective formation constants of species in the nucleotide-seawater system. The results were compared to protonation parameters calculated from single electrolyte systems. A simpler model (SSW considered as a single salt BA, with Bz+ and Az-), representative of the cation (Na+, K+, Ca2+, Mg2+) and anion (Cl-, SO42-) macro-components of seawater respectively, was also used to calculate the overall complexing ability of the seawater salt towards all the systems here investigated.

Hydrolysis and chemical speciation of dioxouranium(VI) ion in aqueous media simulating the major ion composition of seawater

The hydrolysis and chemical speciation of the dioxouranium(VI) ion at 25 °C was studied in a number of binary electrolytes (LiCl, NaCl, MgCl 2, CaCl 2, Na 2SO 4) and some mixtures (NaCl–Na 2SO 4, NaNO 3–Na 2SO 4, CaCl 2–MgCl 2) as well as artificial seawater (SSWE) as a function of ionic strength. The results in LiCl, CaCl 2 and MgCl 2 solutions confirmed the formation of (UO 2) 2(OH) 2 2+, (UO 2) 3(OH) 4 2+, (UO 2) 3(OH) 5 + and (UO 2) 3(OH) 7 − species (at I=0 mol l −1: log T β 22=−5.76, log T β 34=−11.82, log T β 35=−15.89 and log T β 37=−29.26). For NaNO 3, NaCl and artificial seawater the hydrolysis constant for the formation of the UO 2(OH) + species was also determined (at I=0 mol l −1: log T β 11=−5.19). The results in Na 2SO 4, Na 2SO 4/NaNO 3 and Na 2SO 4/NaCl required the formation of UO 2(SO 4) 0, UO 2(SO 4) 2 2−, UO 2(OH)SO 4 −, (UO 2) 2(OH) 2SO 4 0, (UO 2) 3(OH) 4SO 4 0 and (UO 2) 3(OH) 5SO 4 −, whose estimated values of each complex formation constant at I=0 mol (kg H 2O) −1 are (log T β pqr ±standard deviation, species in parenthesis): 3.32±0.02 [UO 2SO 4 0], 4.26±0.04 [UO 2(SO 4) 2 2−], −2.30±0.01 [UO 2(OH)(SO 4) −], −2.64±0.04 [(UO 2) 2(OH) 2(SO 4) 0], −8.45±0.04 [(UO 2) 3(OH) 4(SO 4) 0], −13.58±0.04 [(UO 2) 3(OH) 5(SO 4) −]. All the results were examined using the Pitzer model by considering the interactions of the cation hydrolytic species with Cl − and NO 3 − and anion hydrolytic species with Li +, Na +, Ca 2+ and Mg 2+ and, in addition, the “same sign” and “triple” interaction parameters. The resulting Pitzer parameters give an adequate representation of all the hydrolysis constants measured in the binary, ternary and artificial seawater solutions. Alternatively to the interpretation of the dependence of uranyl hydrolysis constants on ionic strength and on ionic medium in terms of variations of activity coefficients of ions, the formation of ion pairs was considered and some complex formation constants among dioxouranium(VI) species and different ions of background salts were calculated. Interactions of uranyl with major components of seawater were taken into account using the “single salt” BA approximation according to which SSWE is considered as a single sea salt (BA) where cation B and anion A, having charge z=± I/C BA =±1.117 , are representative of all major cations (Na +, K +, Ca 2+, Mg 2+) and anions (Cl − and SO 4 2−) of seawater, respectively. Pitzer parameters were also calculated for both the interactions of uranyl with B z+ and A z− ions and for the internal BA interactions. The last ones are: β (0)=0.1081 and β (1)=0.4238 for B 1.117+–A 1.117− interactions, and β (0)=−0.3134 and β (1)=1.5375 for H +–A 1.117− interactions. Literature data were collected carefully, and a critical analysis and accurate comparisons with results presented here were made.

Occurrence of immature Culicoides molestus (Skuse) (Diptera: Ceratopogonidae) in relation to habitat characteristics

Abstract Analysis of beach sites on the Gold Coast, Australia, found that 14 physical and chemical habitat characteristics differed significantly between sites where numerous immatures of the canal biting midge, Culicoides molestus (Skuse), were found and sites where no midge immatures occurred. Five of the chemical factors found to reliably distinguish C. molestus habitat are major components of seawater, while another, electrical conductivity, is related to the concentration of seawater components. Calcium was the only one of the six primary components of seawater that was not a statistically significant correlate of C. molestus habitation by sand analysis. It is likely that a causative variable in occurrence of immatures is the concentration of seawater present in canals, because larvae are found where seawater component concentration is low in relation to uninhabited sites of similar appearance.

Speciation of polyelectrolytes in natural fluids: Protonation and interaction of polymethacrylates with major components of seawater

Acid–base properties of two sodium polymethacrylates ( W=4000 and 5400 Da) were studied potentiometrically in aqueous solution at 25 °C. Measurements were made in different salt solutions: LiCl 0.1–1.5, NaCl 0.1–2, KCl 0.1–2, Et 4NI 0.1–0.75 mol l −1, and in artificial seawater in the salinity range 10≤ S≤45. Protonation data were analysed by two different models and the dependence of the relative parameters on ionic strength were calculated. Measurements performed in interacting media (alkali metal chlorides and artificial seawater) were interpreted in terms of complex formation, and the relative formation parameters are reported. Previous data on the interaction of a higher molecular weight ( W=230 000 Da) polymethacrylic acid with alkaline metal cations and Ca 2+ were reanalysed in the light of correct procedure which takes the effective polyanion charge into account. The speciation of methacrylates, in aqueous solutions containing the major constituents of natural fluids, is discussed in relation to the various parameters that influence the stability of different species formed.

Protonation Constants and Association of Polycarboxylic Ligands with the Major Components of Seawater

Apparent protonation constants, log βjH*, of 11 carboxylic acids were determined potentiometrically ([H+]-glass electrode) in artificial seawater containing six of the major components (Na+, K+, Mg2+, Ca2+, Cl-, and SO42-) at different salinities: S (‰) = 5, 15, 25, 35, 45. Values of log βjH* were fitted by the simple polynomial equation log βjH* = log TβjH + a1S1/2 + a2S + a3S3/2 (log TβjH = protonation constants at infinite dilution; a1, a2, a3 = empirical parameters), for mono-, di-, and tricarboxylates. For carboxylic anions with charge < −3, a better fit was obtained using the equation log βjH* = log TβjH + b1I + b0z* log(1 + b2I) (b0, b1, b2 = empirical parameters, z* = square sum of reactants minus square sum of products). The potentiometric data were also interpreted in terms of complex formation between the cationic component of artificial seawater and the carboxylic anion (also partially protonated) using the single-salt approximation (the artificial seawater considered as a single salt with B1.117+ cation and A1.117- anion). Calculations were also performed, for comparison, on potentiometric data for phenolic compounds (already published) to obtain the formation constants of seasalt complexes. Generally, both empirical parameters for dependence on ionic strength and complex formation constants are dependent on the charge of the (poly)carboxylic anions. Some useful stability−charge and stability−structure relationships are reported. The interaction of carboxylic ligands with the major components of seawater is discussed in relation to speciation problems.

Speciation of low molecular weight ligands in natural fluids: protonation constants and association of open chain polyamines with the major components of seawater

The interaction of five open chain polyamines (ethylenediamine (en), diethylenetriamine (dien), trietylenetetramine (trien), tetraethylenepentamine (tetren), spermine (sper)) with the major components of seawater was studied potentiometrically at 25°C, in an artificial seawater (containing Na +, K +, Mg 2+, Ca 2+, Cl − and SO 4 2−) at different salinities (5–45‰). Potentiometric data were interpreted in terms of both the apparent protonation constants of polyamines and the formation constants of complexes formed by unprotonated or protonated amines and the cation and the anion of seawater (the inorganic content of seawater being considered as a single 1:1 salt). Some empirical relationships, involving the polyammonium cation charge and the ratio between N and C atoms in the amine, are reported. These relationships have quite a good predictive value. The association ability of seawater salt towards amines is quite significant: at pH 8.2 and 35‰ salinity formation percentages range between 50 and 80%. Speciation problems are discussed.

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.

The single salt approximation for the major components of seawater: association and acid–base properties

In this note we propose the use of the single salt approximation for the composition of seawater. This approximation has been applied to a synthetic seawater. Association and acid-base properties have been determined.

Comparative study of magnesium nitrate, palladium nitrate and reduced palladium for the direct determination of mercury in sea water by electrothermal atomization atomic absorption spectrometry

A comparative study of different chemical modifiers in graphite furnace atomic absorption spectrometry for the direct determination of mercury in sea water samples, in synthetic sea water sample of high (72.8%) and low 34.2%) salinity and in aqueous solutions, was carried out. The use of reduced palladium produces better results. The mixture of palladium nitrate and ascorbic acid, gives the best limit of detection (1.9 μgl−1). The use of reduced palladium and magnesium nitrate produced excellent recoveries (close to 100%) in the whole salinity range for all mercury concentration tested. The use of palladium nitrate alone or combined with magnesium nitrate gave good recoveries with respect to a real sea water sample for low salinities. The interference from the major components of sea water were completely removed by using reduced palladium and magnesium nitrate modifiers. Thus, a single calibration curve with synthetic sea water may be applied to the analysis of sea water samples of widely differing salinities.

Study of chemical modifiers for direct determination of silver in sea water by ETA-AAS with deuterium background correction

Methods for the direct determination of silver in sea water samples by ETA-AAS using different chemical modifiers were studied. The effect of salinity was studied using synthetic sea water of high (72.8‰) and low (34.2‰) salinity, and the results were compared with aqueous standard solutions. The charring temperatures achieved were 800 and 900 °C for magnesium nitrate and ammonium dihydrogen phosphate respectively, being 1100 °C for palladium nitrate and their mixtures. The best sensitivity obtained in the peak-height measurement mode was achieved by using reduced palladium (limit of detection (LOD) between 0.5 and 1.1 μg l −1 for an injection volume of 20 μ1) with analytical recoveries close to 100% for synthetic and real sea water samples. The use of ammonium dihydrogen phosphate (LOD of 1.3 μg l −1 for an injection volume of 20 μ1) produced good recoveries for low salinity; at high salinity an increase of around 25% was obtained, the method being unsuitable for sea water analysis. Finally, an interference study of the major components of sea water was carried out and applied to the analysis of surface sea water from the Galicia coast.

Electrochemical speciation of organotin compounds in water and sediments. Application to sea water after ion-exchange separation

For the quantitative speciation of tributyltin, Bu3Sn+ (TBT), in the presence of dibutyltin, Bu2Sn2+ (DBT), monobutyltin, BuSn3+ (MBT), triphenyltin, Ph3Sn+ (TPT), and inorganic tin in water samples and sediments, an accurate, reproducible, simple and rapid electrochemical method was developed. After extraction of the organotin compounds with dichloromethane, TBT could be selectively determined as species by alternating current polarography directly in the organic phase without any derivatisation. The successful application of this technique could be proved by the results obtained by intercomparison exercises on TBT in water samples and sediments, organized by the Community Bureau of Reference (BCR). For the application of this technique to sea water samples a preliminary ion exchange separation of TBT from the major components of sea water was performed, achieving a detection limit for TBT in the ppt range.

The Use of Sea Water in Well Cementing

The performance of cement slurries using sea water can be predictable to a safe degree. Using sea water reduces placement time, increases early strength development, and shortens waiting-on-cement time. The effects of sea water on accelerators, retarders, fluid loss, and dispersant additives are discussed. Introduction This study shows that if sea water is used in place of fresh water for mix water in cementing systems, the setting rate of cement is accelerated. This affects cement thickening time, early strength development, and waiting-on-cement time. Using sea water also affects the prehydration of bentonite and the activity of accelerators, retarders, fluid loss, and dispersant additives. Also, improved bonding characteristics are indicated. Uncontaminated waters from seven oceans under current drilling activity are analyzed and are shown to be very similar in composition. For preliminary laboratory testing with cements, the composition of sea water can be approximated by the ASTM standard sea water. Also, a complete analysis of a specific sea water can be obtained by measuring only the chloride content. The other major constituents can be calculated from this chloride ion. Other investigators have found that, for most practical purposes, the ratios of all major components of sea water to chlorides are constant. Cement slurries for well completions generally perform best when mixed with fresh water. It is generally believed that if the water is potable, it is satisfactory for cements. This practice is followed generally on land operations, where practical and economical, and has been the practice in practical and economical, and has been the practice in several offshore areas. However, with increased offshore drilling activities, the use of sea water for mixing cement slurries for down-hole cementing applications has increased significantly. Sea water is being used as the mix water for casing, liner, and squeeze cementing operations. Also, because of the large loads placed on offshore platforms, it is now the practice in many cases to grout the piles to the jacket structures for effective load transfer. Some of these grouts are mixed with sea water. The reasons for this increased application of sea water become readily apparent when the advantages of sea-water cementing are examined. The advantages includeready availability,lower costs because transportation is eliminated, andreduced fresh-water storage on offshore platforms. Perhaps the most significant effect on cement performance is caused by the presence of sodium chloride in performance is caused by the presence of sodium chloride in sea water. The effect of sodium chloride on physical properties of oilwell cements has been discussed by Ludwig properties of oilwell cements has been discussed by Ludwig and by Slagle and Smith. These are both excellent presentations on the effect of sodium chloride, but generally presentations on the effect of sodium chloride, but generally only limited data on sea water were included, or the concentration of the salt studied was considerably higher than salt concentration in sea waters. Therefore, a better definition of the effects of sodium chloride and other salts in sea water on the various physical properties of cement in the slurry state and the set state was required. Sea-Water Composition The concentration of dissolved materials in ocean water varies with location and with seasons of the year. Sea water is diluted by rivers, rain, or melting ice, or is concentrated by evaporation. Sea water also contains all types of suspended material, such as colloidal and larger particulate minerals, insoluble organic compounds, and particulate minerals, insoluble organic compounds, and living creatures. JPT P. 759

Heat capacity of seawater solutions from 5° to 35°C and 0.5 to 22‰ chlorinity

The specific heat of seawater solutions from 0.5 to 22‰ chlorinity has been determined at 5°, 15°, 25°, and 35°C by using a new precision heat capacity calorimeter (Picker et al., 1971). The concentration dependence Cl (‰) of the specific heats cp has been fit to cp = cp° + ACp Cl (‰) + BCp Cl (‰)3/2, where cp° is the specific heat of pure water and ACp and BCp are temperature-dependent constants. The specific heats fit this equation with an average deviation of ±0.0002 joule deg−1 g−1 between 15° and 25°C and ±0.0005 joule deg−1 g−1 at 5°C. The specific heats determined in this study are in excellent agreement (±0.002 joule deg−1 g−1) with the results of Cox and Smith (1959) and Bromley et al. (1967, 1970). The apparent equivalent heat capacity ΦCp for sea salt has been determined from these heat capacities, and the concentration dependence (Im is the molal ionic strength) has been analyzed by ΦCp = ΦCp° + SCpIm1/2 + bCpIm, where ΦCp° is the infinite dilution equivalent heat capacity of sea salt (related to ion-water interactions), SCp is the Debye-Huckel limiting law slope (related to ideal ion-ion interactions), and bCp is an empirical constant (related to deviations from the Debye-Huckel limiting law). The relative apparent equivalent heat capacity ΦJ = ΦCp − ΦCp° calculated from our results is in good agreement with the temperature dependence of the enthalpy of seawater ΦJ = ∂ΦL/∂T calculated from the apparent equivalent enthalpy data ΦL of Millero et al. (1973). Young's (1954) rule, ΦCp = ∑EiφCp(i), has been used at 25°C to estimate the ΦCp of sea salt by using data on the major components of seawater in pure water. The estimated ΦCp and cp are in excellent agreement with the measured values.

Thermodynamic properties of sea water and its concentrates

A systematic study of the properties of aqueous solutions of the major components of sea water, NaCl,KCl,Na 2SO 4and MgSO 4 is being carried out in the Boston Laboratory of Monsanto Research Corporation, under the sponsorship of the Office of Saline Water, U.S. Department of the Interior. Densities, vapor pressures, and viscosities of binary and ternary solutions were measured at concentrations corresponding to that of sea water and its concentrates up to five-fold concentration over the 25 to 150 C or 175 C temperature range. The experimental methods used are described. The experimental data and literature data on all these properties of sea water and its concentrates were correlated to permit easy interpolation. Methods for estimating these properties for sea water, its concentrates, and brines were developed and recommended data are presented. This work substantially extends the range of data available and represents a systematic attempt to provide data for desalination practice.