Solubility in seawater

Seawater contains dissolved inorganic salts. An aqueous solution of about 35 gL-1 NaCl is often taken as a model solution for seawater. The salt effect on the solubility of nonelectrolyte organic compounds has been investigated systematically by Sechenov [68] and by Long and McDevit [69]. Correlations between pure water solubility, Sw, and the solubility at different salt concentrations are compound dependent. For example, the seawater solubility, 5SW, of PAHs are from 30 to 60% below their freshwater solubilities [1], depending on the particular structure of the PAH. We concentrate our interest on the question if, for certain compound classes, Ssw can be estimated from known Sw without any input of further compound-specific parameters. 

Sutton and Calder [70] measured Sw and Ssw for several n-alkanes and alkyl benzenes at 25°C and reported that in all cases Ssw Sw. Similarly, Groves [71] found that the salt water solubility (34.5 parts of NaCl per thousand parts of water) at 25° C 

A salting-out effect occurs for alkanes, cycloalkanes, alkylbenzenes,, R 11 1. 

A quantitative correlation has been derived based on experimental data for 11 aromatic compounds (biphenyl, naphthalene, anthracene, phenanthrene, pyrene, phenol, p-toluidine, p-nitrotoluene, and o-, m-, and p-nitrophenol) at 20°C [74]  

Solubility in Water, in Handbook of Chemical Property Estimation Methods, W. J. Lyman, W. F. Reehl, and D. H. Rosenblatt, Editors, 1990. Washington, DC American Chemical Society. 

---

The vast majority of bioassays on marine organisms have been conducted on toxicants that are soluble in seawater. Because drilling mud contains solid particles, a special procedure had to be developed. 

For the solubility in seawater of oxygen, nitrogen and carbon dioxide at various temperatures and chlorinities refer to Tables 21.21 and 21.22. 

Carbon dioxide is likewise an inert material. As a result, its only known sinks are photosynthesis and solubility in seawater. The cycle of carbon dioxide through the atmosphere will be a major focal point in Chapter 11. 

Radium, like most other group II metals, is soluble in seawater. Formation of Ra and Ra by decay of Th in marine sediments leads to release of these nuclides from the sediment into the deep ocean. Lead, in contrast, is insoluble. It is found as a carbonate or dichloride species in seawater (Byrne 1981) and adheres to settling particles to be removed to the seafloor. 

For most organic chemicals the solubility is reported at a defined temperature in distilled water. For substances which dissociate (e.g., phenols, carboxylic acids and amines) it is essential to report the pH of the determination because the extent of dissociation affects the solubility. It is common to maintain the desired pH by buffering with an appropriate electrolyte mixture. This raises the complication that the presence of electrolytes modifies the water structure and changes the solubility. The effect is usually salting-out. For example, many hydrocarbons have solubilities in seawater about 75% of their solubilities in distilled water. Care must thus be taken to interpret and use reported data properly when electrolytes are present. 

Statham [448] has optimised a procedure based on chelation with ammonium dithiocarbamate and diethylammonium diethyldithiocarbamate for the preconcentration and separation of dissolved manganese from seawater prior to determination by graphite furnace atomic absorption spectrometry. Freon TF was chosen as solvent because it appears to be much less toxic than other commonly used chlorinated solvents, it is virtually odourless, has a very low solubility in seawater, gives a rapid and complete phase separation, and is readily purified. The concentrations of analyte in the back-extracts are determined by graphite furnace atomic absorption spectrometry. This procedure concentrates the trace metals in the seawater by a factor of 67.3. 

Wasik SP, Brown RL (1973) Determination of hydrocarbon solubility in seawater and the analysis of hydrocarbons in water-extracts. In Proceedings of the conference on prevention and control of oil spills. American Petroleum Institute, Washington, DC, pp 223-237... 

It is emphasized that Cr+3, probably because of its very low solubility in seawater, appears to have a much lower bioavailability to most groups of marine animals than Ct 6, which is more water soluble (Carr et al. 1982). The clam Rangia cuneata appears to be an exception it accumulated up to 19 mg Cr/kg in soft parts, on a dry weight basis, during exposure for 16 days to chromium-contaminated muds, and retained most of it for an extended period the estimated biological half-time was 11 days (Carr et al. 1982). In general, benthic invertebrates rarely accumulate chromium from contaminated sediments (82 to 188 mg Cr+Vkg) only a few examples have been recorded (Neff etal. 1978). 

The density of crude oil is on the order of 0.85 g/cm, so if the sea surface is calm, an oil spill will initially form a slick. The slick is subject to physical processes, such as advection and turbulence, causing it to move vertically and/or horizontally. Advection tends to lead to dispersal or, if land is nearby, shoreline stranding. Turbulence promotes the formation of emulsions, called chocolate mousse, which can be transformed via weathering into tarballs. The lower-molecular-weight compounds tend to evaporate or dissolve. Some fractions of petroleum have solubilities in seawater on the order of tens of milligrams per liter. Some are also photochemically oxidized. 

Ra, Sb, and Th (Joshi 1991). Radiocesium-137 in water from the Hudson River esmary. New York, decreased tenfold between 1964 and 1970, but the Cs content in fish and in sediments remained relatively constant (Wrenn et al. 1971). The effluent from the United Kingdom s Atomic Energy Agency SeUafield facility on the Cumberland Coast of the Irish Sea contained °Sr and Cs, which are soluble in seawater and tend to remain in solution, and Ru, and Zr/ Nb, which are relatively insoluble in seawater and coprecipitate or adsorb on free inorganic and organic surfaces (Pentreath etal. 1971). 

Hi) pytkowicz, R. M., Disteche, A., and Disteche, S. Calcium carbonate solubility in seawater at in situ pressures. Earth. Plan. Sci. Letters 2, 430-432 (1967). 

In the previous chapter, the fact that stoichiometric and apparent constants have been widely used in seawater systems was discussed. Berner (1976) reviewed the problems of measuring calcite solubility in seawater, and it is these problems, in part, that have led to the use of apparent constants for calcite and aragonite. The most difficult problem is that while the solubility of pure calcite is sought in experimental seawater solutions, extensive magnesium coprecipitation can occur producing a magnesian calcite. The magnesian calcite should have a solubility different from that of pure calcite. Thus, it is not possible to measure pure calcite solubility directly in seawater. 

The central question was, how major is the influence of coprecipitated magnesium Berner (1976) used a clever approach to find out. His reasoning was that whereas calcite has a major coprecipitate from seawater (Mg) capable of altering its solubility, aragonite that can be precipitated from seawater is greater than 99% pure, and its solubility in seawater should be measurable. He also pointed out that if the solubility ratio of calcite to aragonite was precisely known, it would... 

Kuma K, Nishioka J, Katsuhiko M (1996) Controls on iron(ni) hydroxide solubility in seawater the influence of pH and natural organic chelators. Limnol Oceanogr 41 396 107... 

Two metallic components of drilling muds, barium and chromium, have been studied for their impact on bivale molluscs44. Generally, chromium bioaccumulation is limited to forms soluble in seawater, whereas barium, present as insoluble BaS04, is assimilated with a resultant elevated level in selected organs of the molluscs45,46. ... 

Byrne, R. H. Jr. "Iron speciation and solubility in seawater," Ph. D. Thesis, Univ. Rhode Island, Kingston, R.I., 1974. 

Because N2 is a non-polar molecule, its solubility in seawater is low. Based on new measurements, Hamme and Emerson (2004) recently presented an improved equation for the Bunsen solubility of N2 dissolved in seawater in equilibrium with a moist atmosphere at 1 atm (Cnj in pmol kg ) ... 

Garcia, H. E., and Gordon, L. I. (1992). Oxygen solubility in seawater. Better fitting equations. Limnol. 

Unsatisfactory physicochemical stability of the sorbent. Titanium hydroxide is slightly soluble in seawater (0.1 mg/1 [165]) and also shows some degradation upon aging. Mixed titanium and zirconium oxide-type sorbents, known as thermoxides with much better stability [178, 179] were developed. 

Halides (fluorine, chlorine, bromine, and iodine). Fluorine as F substitutes readily for OH in hydroxy minerals, implying that it probably occurs in all nominally anhydrous minerals in the same way as OH. Fluorine is not significantly soluble in seawater. Both these properties make its geochemical behavior quite different from the other halides. F/K and F/P ratios in basalts are reasonably constant (Smith et al, 1981 Sigvaldason and Oskarsson, 1986) with ratios of 0.09 0.04 and 0.29 0.1, respectively. Both ratios yield the same value of 25 ppm for the PM abundance which is listed in Table 4. However, the F/K ratio in the continental crust appears distinctly higher and the F/P ratio lower (Gao et al, 1998), indicating that the incompatibility of these elements increases in the order P < F < K. 

Another problem is the determination of aragonite solubility in seawater. A study of the solubility of calcite and aragonite in seawater... 

Hiickel theory [or the Giintelberg or Davies equation (Table 3.3)] may be used to convert the solubility equilibrium constant given at infinite dilution or at a specified / to an operational constant, valid for the ionic strength of interest. In seawater solubility equilibrium constants, experimentally determined in seawater, may be used. For example, the CaC03 calcite solubility in seawater of specified salinity may be defined by = [Ca " ] [CO f ], where [Caj ] and [C03f ] are the total concentrations of calcium and carbonate ions, for example,... 

Example 7.9. Effect of Pressure and Temperature on Calcite Solubility in Seawater An enclosed sample of the surface seawater, as discussed in Example 7.8 (25°C pH = 8.2 [Ca ] = 1.06 x 10" M [Carb-Alk] = 2.4 x 10" eq liter" ), is cooled to 5°C and then subjected to increases in total pressure of up to 1000 atm (equivalent to exposing the sample to increased water depths of approximately 10,000 m). How does the composition, pH, [CO3"], [Ca "], and extent of oversaturation change as a result of the temperature change at 1 atm and as a result of the pressure change at 5°C The water is incipiently oversaturated with respect to calcite. Assume that CaC03... 

Weiss, R., 1981. On the International Oceanographic Tables, Vol. 2, Unesco 1973, Oxygen Solubility in Seawater. Unesco technical papers in marine science 36, 22. 

---