Salinity range

Wilson [32] has described a portable flow-cell membrane salinometer. Although test solutions are normally passed through the cell, the electrodes can be connected to a remote membrane sensor head by means of salt bridges for measurement of the salinity of estuarine muds in situ. The error is within 1% over the salinity range 1 - 40%. 

The manifold design allows for the determination of ammonia concentration in the range 0.2-20 xg/l as NH4 over a salinity range 35- 10%o, with negligible interference from amino acids. 

Ice-brine slush, essentially a slurry of ice crystals in brine, the over-all salinity ranging from that of the feed water down to about one half of this value. 

The conditional stability constants calculated for the different salinity ranges are given in Table 5. It looks as if in the more saline samples complexes with lower K are formed. 

In order to reduce the abundance of malarial mosquitoes in the swampy regions of Colchis, intentional introduction of the mosquito fish Gambusia holbrooki (Girard, 1859) was made. The mosquito fish was brought from freshwater regions of Italy in 1925 [57] and was successfully introduced into the wetlands of the Black Sea. The mosquito fish dwells in brackish estuaries meanwhile, it behaved as an euryhaline species and expanded over the Azov-Black Sea basin. At present, it occurs in a wide salinity range from 0 to 15-17%o. 

Fig. 5 Daily specific growth rates of total DMS + DMSPd + DMSPp versus specific cell growth in a variety of axenic Phaeocystis globosa batch cultures under different conditions. Cultures were grown at the same temperature (11°C), but with different salinities, nutrient ratios and/or light conditions. Specific growth rates were calculated per day. Culture growth details are as follows N-sal salinity range from 25 to 50 PSU, nitrogen limited P-sal salinity range from...

The two predominant processes that affect lake water composition are evaporation and biological processes. In dry zones, evaporation has important effects on the composition of lake water, concentrating one type of ion more than others and favoring precipitation reactions of other ions, sometimes deriving in highly saline lakes. Approximately 46-48% of the water in lakes is contained in saline lakes. In most freshwater lakes, salinity ranges from 0.1 to 0.5 g/L. 

For most of the AES surfactants studied, the ratio of foam volume in the presence of added decane to that in its absence was relatively constant over the 0.5X-1.5X salinity range but decreased significantly when the solvent was 2.OX brine. 

Empirical curves were fit to data (22) giving values and K2 over 5-30°C temperature and 2-4 percent salinity ranges. 

The most common alternative to the phenol-hypochlorite method uses OPA. This technique was introduced in an automated version based on the conversion of NH4+ to NH3, which is then allowed to diffuse across a membrane into a flowing stream of OPA to form a fluorescent product (Jones, 1991). This final product is then analyzed fluorometricaUy with a detection limit of 1.5nM (Jones, 1991). Advantages of the method are that it requires only a single reagent and it has a lower detection limit than the standard phenol-hypochlorite method. Furthermore, the salt effect is relatively small (<3% over a salinity range of 0—35 %o) and there is no interference from primary amines. The technique has been modified to remove the gas diffusion cell, also with a reported detection hmit of 1.5 nM (Kerouel and Aminot, 1997) a manual version has also been published (Holmes et al, 1999). 

Some studies have reported conservative behavior during estuarine mixing. In the unpolluted Krka Esmary of Yugoslavia, Seyler and Martin (1991) observed a linear increase in total arsenic with increasing salinity, ranging from 0.13 xgL in freshwaters to 1.8 JLgL offshore. Other studies however, have observed nonconservative behavior in estuaries due to processes such as diffusion from sediment pore waters, co-precipitation with iron oxides, or anthropogenic inputs (M. O. Andreae and T. W. Andreae, 1989 Andreae et al., 1983). The flocculation of iron oxides at the freshwater-saline interface as a result of increase in pH and salinity can lead to major decrease in the arsenic flux to the oceans (Cullen and Reimer, 1989). 

Salinity remains relatively constant in some lakes, while it tends to increase significantly in others. A lake that has outflow, such as a runoff stream, keeps within a normal salinity range for that lake. But lakes that have no runoff lose water over time to evaporation, and a higher salinity results. 

Samples are grouped within salinity ranges covering no more than 5%o (smaller for low salinity samples). Spiked standards are prepared in representative seawater samples from each of these ranges. 

In hot climates, evaporation rates are high and ocean salinity ranges on the upper end of the scale. In the Red Sea and Persian Gulf, salinity may reach 42 percent. Salinity is also elevated in places where little or no new freshwater enters the system, or where water is trapped without a natural outlet. In the Dead Sea, water flows in from the Jordan River, but it has no path by which to leave the system. 

The physicochemical aspects of micro- and macroemulsions have been discussed in relation to enhanced oil recovery processes. The interfacial parameters (e.g. interfacial tension, interfacial viscosity, interfacial charge, contact angle, etc.) responsible for enhanced oil recovery by chemical flooding are described. In oil/brine/surfactant/alcohol systems, a middle phase microemulsion in equilibrium with excess oil and brine forms in a narrow salinity range. The salinity at which equal volumes of brine and oil are solubilized in the middel phase microemulsion is termed as the optimal salinity. The optimal salinity of the system can be shifted to a desired value hy varying the concentration and structure of alcohol. 

PDM-337/TAA. In this system, aqueous solutions, prepared from d ionized and triple-distilled water, contained 9.0% by volume of a 63/37 weight-ratio mixture of PDM-337 surfactant (Exxon) and reagent grade tert-amyl alcohol (TAA). The surfactant is 84% active and is primarily the monoethanolamine salt of dodecyl orthoxylene sulfonic acid. Samples were prepared in the salinity range of 0.4 to 2.6 gm NaCl/dl surfactant solution. The NaCl was reagent grade. 

TRS 10-410/IBA. Solutions containing 5.0% by weight TRS 10-410 surfactant (Witco) and 3.0% reagent grade isobutyl alcohol (IBA) were used in the salinity range of 0.7 to 2.3 gm/dl. The surfactant is a 61.5% - active mixture of petroleum sulfonates with an equivalent weight of 424. 

Based on literature correlations (14), an estimate of the phase volume scan with n-undecane is also plotted. The decrease in hydrocarbon chain length moves the optimum to approximately 1.5 gm/dl salinity, which, like the PDM system, is near the center of the S+L regime. Also, the volume of the middle phase is predicted to increase, while the three-phase salinity range is predicted to shrink slightly. 

The dynamic behavior of the PDM system in the salinity range between optimum salinity and the upper-phase microemulsion region was similar to that below optimum in that intermediate brine and microemulsion phases formed. Figure 13 shows these phases for the 1.5 gm/dl-salinity PDM system. The middle-phase type of microemulsion, being high in oil content at these salinities, grew more rapidly in the direction of the oil phase than it did at low... 

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