Salt crust

Salz-rinde, /. salt crust, -riickstand, m. salt residue, -salpetersaure, /. nitrohydrochloric acid, aqua re a. 

Assume fouling factors. Inside tube factors can be selected from Table 10-12 or 10-13 or by referring to Table 10-15. Because the water rate is low over these coolers, they may develop salt crusts, scale, algae, etc. therefore, the values of fouling will be high, see Table 10-35. 

The salt-crusted surfaces of the brackish lakes in the South Plains of West Texas are said to contain proportions of potash which can be profitably extracted. 

Small crystals of salts are occasionally seen to cover the soil and rocks near springs and seepages. In arid regions such efflorescences, or salt crusts, are also seen on soils in areas detached from springs or other types of surface water. 

Low pH (< 4,5, possibly as low as 2) of water in springs, seeps, open cuts and streams draining from the mine site, Extensive vegetation death, yellow or white salt crusts on the soil surface, pale blue cloudy appearance of surface water... 

Abundant yellow or white salt crusts are present on waste rock and at the surface of the soil. The crusts comprise alum-like sulfate minerals containing variable amounts of sodium, potassium, iron and aluminium, such as the mineral jarosite. They are often very soluble in water, releasing acid and precipitating ferric hydroxides. 

Inadequate heat transfer can be caused not only by an air space, but to an even greater extent by salt crust formation on the inside of the vessel. Hence, mixtures from which salts separate must always be stirred, and the stirrer should come as near to the walls as possible in order to keep them free from incrustation. When large amounts of salt separate, even the best stirrers are inadequate. One case is known where a salt crust only 4 cm. thick resulted in overheating an autoclave to the point where it was red hot. At an internal temperature of 240°C. and pressure of 48 atmospheres, the autoclave was blown out like a balloon and the bottom split. The escaping gas cooled the steel enough so that no further danger was involved. It is almost certain, however, that cast iron would have exploded. (Fusions such as those in the preparation of -naphthol, if done without a metal bath, would certainly ruin any pressure vessel.)... 

Pseudomorphs after halite are common throughout the McArthur Group. The halite appears to have formed by almost complete evaporation of seawater in shallow marine environments and probably represents ephemeral salt crusts. The general lack of association of halite and calcium sulfate minerals in these sediments probably resulted in part from the dissolution of previously deposited halite during surface flooding, but also indicates that evaporation did not always proceed beyond the calcium sulfate facies. 

Northwest Utah is the site of the Bonneville Salt Flats—an area covered with a hard, flat, salt crust that formed in ancient times. Located near F80, the salt flats cover 46 square miles (119 square kilometers) and are mainly comprised of sodium chloride (common table salt). The flat landscape, which is home to the Bonneville Speedway, has helped many auto racers set speed records for nearly 100 years. IMAGE COPYRIGHT 2009, MDD. USED UNDER LICENSE FROM SHUTTERSTOCK.COM. 

Salt crust Silica glaze manganese and iron oxides The precipitation of chlorides on rock surfaces Usually clear white to orange shiny luster, but can be darker in appearance, composed primarily of amorphous silica and aluminum, but often with iron... 

Lacustrine deposits (a) perennial saline lake, (b) salt crust or saline pan, (c) saline mudflat, (d) dry mudflat and (e) shoreline commonly arranged in sequence outwards from the centre of a lake basin (Figure 10.3B and Figure 10.4). 

The various playa environments include a central salt crust or saline pan, composed of dry salt, commonly halite (Figure 10.3D, E), but in some cases trona (Eugster, 1970), gypsum (Stoertz and Ericksen, 1974) or other sulphates such as mirabilite, epsomite or bloedite. The saline mudflat is typically moist clay to silt with surface salt efflorescences and intrasediment (displacive) evaporite minerals. In some systems, these may be zoned on a broad scale, with more-soluble minerals towards the lowest central portion of the mudflat, caused by groundwater evaporation gradients (e.g. Saline Valley, California Hardie, 1968). 

More specific palaeotemperature data for individual halite crystals may be gleaned from fluid inclusion homogenisation temperatures, a technique which has been substantially refined since the 1990s (Roberts and Spencer, 1995 Lowenstein and Brennan, 2001). From a core spanning lOOka of saline deposition in Death Valley, Lowenstein et al. (1998) were able to reconstruct depositional temperatures for several intervals (with an expected lower value, at the Last Glacial Maximum), and to faithfully recover the known seasonal temperature range for a modern salt crust. 

Risacher, F. Fritz, B. (2000) Bromine geochemistry of Salar de Uyuni and deeper salt crusts, central Altiplano, Bolivia. Chemical Geology 167, 373-392. 

Thus, the basic processes of seasonal dynamics of the territory of a former sea bottom are coimected to a regime of moistening and salinization, drying of the ground and formation and then destruction of salt crusts on the edge of the narrowed humidified strips. 

Fig. 18 Series of maps of seasonal changes of natural complexes in 2002 (a) 16 April (b) 18 May (c) 10 July (d) 19 September. 1 - Marsches (alternations of sites of water and dried bottom). Loamy-silty waste lands and sand/salt deserts on a former sea bottom 2 - strong wet 3 - wet 4 - dry. 5 - Salt crusts at the edge of wet strips of a former sea bottom. 6 - Deposits of deflated salts...

F. 19 Seasonal changes in humidity and salinization of a former sea bottom in 2002. ShOTeline 1 - in 1961, 2 - in 2002. Parts of former sea bottom 3 - strong wet, 4 - moderate wet, 5 - dry. 6 - salt crusts. 7 - plots with salt accumulation after salt crust erosion by wind... 

Table 5 The structure of microalgal coenoses from stations of the Western and Eastern basin (June 2008). At St.A-08-06 crystalline pnlp there were fragments of a salt crust up to 2-...

In October 2005, the salinity in the channel was above 130 ppt for the first time. We observed two species of euglenids (Euglena texta var. salina and Euglena cf. pasheri [58]) in the extended shallow water areas covered with chloride salt crust. 

In June 2008 we managed for the first time to study algal flora of the central part of the Eastern basin. The depth was 0.2 m, the bottom was covered with a salt crust, and the salinity reached 211 ppt. At that time 18 species of microphytes (Table 2) lived there. Seventeen of them were observed at the same time in the Western basin. The eighteenth - N. sigma -disappeared from its coenoses in 2006. 

In 2005, when salinity in the channel reached 130.9 ppt, the relative abundances of Ph. cf. simplex and S. fastuosa increased at the maximal water depth (approx. 5 m) to 6.4 and 10.8%, respectively (Table 12). Also N. phyllepta, a marker of the Western basin, became abundant in the silts of channel shoals (8.5%) but was absent on bare salt crusts deposited at greater depth, fri the northern part of the Eastern basin (salinity 134.06 ppt), at the maximal depth of 3 m, the assemblage consisted of rare N. phyllepta (0.8%) and Ph. cf. simplex (2.5%) cells, and mass... 

Anxious to escape from the heat and the oppressive atmosphere of hundreds of feet below sea level, Sandy stepped on the gas. We roared across the salt-crusted lowlands of the Dead Sea and began to climb into the hills of Judea. Jericho, a colorless hot little town which might have been Mexican or New Mexican, was quickly left behind. 

With evaporative concentration are also associated salts accumulated in soils and ground in the territories with arid climate, in particular, in drainless depressions. They form saline lands (sabkhas, sors, shorts). On the saline surface in such locations often form hard, sometimes fractured salt crust up to 10-15 cm thick. Excessive irrigation for expanding cultivated acreage in conditions of arid climate can cause rise of ground water level and salinization of soils. 

---