Salinity definition

Another item of the forthcoming recommendation by the WG127 concerns a new salinity definition called Reference-Composition Salinity, bringing this fundamental oceanographic measure back into the interdisciplinary scientific and engineering family of the SI system of units (BIPM, 2006 Millero et al., 2008). The chemical Reference Composition is given in Table 20.1. On the basis of this definition, the recommended conversion formula between Absolute Salinity, S, and Practical Sahnity, S, of standard seawater is given by... 

The offered method can be recommended for changing of more laborious and prolonged standard procedures of definition of total water salinity, which are used now. 

Ocean sea water is roughly equivalent in strength to a 3 j % w/v solution of sodium chloride, but it has a much more complex composition, embodying a number of major constituents, and traces at least of almost all naturally occurring elements. For convenience, however, the concentration of salts in any sample of sea water is expressed in terms of the chloride content, either as chlorinity or as salinity. Both these units are again subject to arbitrary definition and do not conform simply to the chemical composition. 

A fully automated instrumental procedure has been developed for analyzing residual corrosion inhibitors in production waters in the field. The method uses ultraviolet (UV) and fluorescence spectrophotometric techniques to characterize different types of corrosion inhibitors. Laboratory evaluations showed that fluorescence is more suitable for field application because errors from high salinity, contamination, and matrix effect are minimized in fluorescence analysis. Comparison of the automated fluorescence technique with the classic extraction-dye transfer technique showed definite advantages of the former with respect to ease, speed, accuracy, and precision [1658],... 

Water with a salinity of less than 10,000 mg/L is considered to be a potential underground source of drinking water. By regulatory definition, deep-well injection of hazardous waste can occur only in very saline waters or brines. Actual salinities of waters in currently used deep-well injection zones vary greatly.70 Normally, the term brine is used to refer to the natural waters in deep-well injection zones. As noted above, however, this term is not technically correct if TDS levels are less than 35,000 mg/L. 

The major ions constitute about 99.8% of the mass of solutes dissolved in seawater. Sodium and chloride alone account for 86%. Thus, seawater is a very salty solution. Early oceanographers invented the term salinity to refer to the mass of dissolved salts in a given mass of seawater. The mathematical form of this theoretical definition is ... 

As with solids, colloids, and solutes, marine scientists have developed practical definitions of salinity that are based on measurement technique. Those in current use are listed in Table 3.2 with their typical measurement precision. Each method has its advantages and disadvantages. For example, refractometers are small, lightweight, and low cost, but have low precision, so they are used for field work in which only a rough... 

The PSS-78 is based on the measurement of a conductivity ratio and, hence, is technically unitless. Nevertheless, some oceanographers use a psu designation to represent a practical salinity unit and others report salinity in units of parts per thousand (%o). The latter convention has been adopted in this text. In any event, it is important to appreciate that the practical salinity is no longer directly traceable to the theoretical definition given in Eq. 3.1. 

Although the GLP revisions of 1987 excluded animal feed and water from the definition of control article, it would appear that such common vehicles as saline solutions and carboxymethylcellulose solutions still fall within the definition. Such a strict definition of the term for such innocuous vehicles as saline solutions is quite burdensome when one considers the requirements for control articles that are found in other sections of the GLPs characterization [ 58.105(a)], stability testing [ 58.105(b)], sample retention [ 58.105(d)], and inventory [ 58.107(d)]. It does not appear that this comprehensive definition is enforced by FDA field investigators in the course of GLP inspections. 

In the following I will present a model to tackle this question. We are at the level of speculations, but we will use some known facts. For example, let s start from the condensation of NCA-anhydrides, a reaction which, as we have seen in the previous chapter, is considered prebiotic. In this way, oligopeptides up to (say) a length of ten can be built, possibly under thermodynamic control, but starting from a definite set of conditions (amino-acid composition in the starting mixture, pH, salinity, etc.). We can assume, and this is actually quite reasonable, that in this way copious libraries of different decapeptides have been formed, each in a significant concentration. 

It may be expected that this disquisition should be commenced by giving a rigid definition of the term salt, or saline substance. But the complex ideas of natural substances are not subject to very definite descriptions, nature in her several productions proceeds by imperceptible gradations, seldom having any decisive marks, by which we can invariably discriminate them into sorts. ... 

Solutions of adrenochrome in the lower alphatic alcohols decompose rapidly in these cases the disappearance of the adrenochrome absorption maximum in the visible region is accompanied by the appearance of the characteristic yellow-green adrenolutin fluorescence and a definite adrenolutin absorption maximum at 405 m/x appears.112 The rate of rearrangement in methanol, ethanol, n-propanol, and u-butanol was about 10 times as fast as in water.112 Feldstein had previously reported that adrenochrome solutions in methanol were less stable than those in water or physiological saline.125... 

Combinations op Silver.—There are three oxides of silver—a suboxide, a protoxide, and a bin oxide. Of these the protoxide alone forms permanent and definite saline combinations. 

The solvent extraction process has not yet undergone pilot plant investigation, and all the above estimates are based on small laboratory or bench scale experiments. If further testing under practical conditions substantiates the laboratory observations, it appears that the solvent extraction process definitely has an area of specialization in the over-all saline water conversion program. 

Even though many of us are familiar with the term fluid, we probably don t know the true scientific definition. You may think that a fluid is a liquid like a normal saline solution. While this is true, a fluid does not have to be a liquid. In the scientific usage of the word, a fluid is any material that has the ability to flow. Thus both liquids and gases are considered fluids. Basic forces, like those that result from gravity or pressure differences, cause fluids to flow. When fluids are placed in a container, they assume the shape of the container, unlike solids that keep their shape. 

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