Hypersalinization

Lee YH, Matthews RD, Pavlostathis SG (2005) Anaerobic biodecolorization of textile reactive anthraquinone and phthalocyanine dyebaths under hypersaline conditions. Wat Sci... 

Woolard CR, Irvine RL (1995) Treatment of hypersaline wastewater in the sequencing batch reactor. Wat Res 29 1159-1168... 

Since sewage seed does not compare favourably with salt-tolerant bacteria in determining the BOD of saline waste waters, a salt-tolerant bacteria seed should be used to ensure an accurate and reproducible BOD value hypersaline waste waters are being tested. 

Other physiological functions of MAAs in phototrophic organisms such as organic osmolytes have been suggested, because very high concentrations can be found in cyanobacteria living in hypersaline environments (Oren 1997). However, salt shock experiments with the marine cyanobacterium Microcoleus chthono-plastes did not indicate ary major involvement of MAAs in the process of osmotic acclimation (Karsten 2002), and hence their proposed function as osmolytes has to be questioned. 

Hydrothermal Of the hot-water systems that are present at acUve mid-ocean spreading centers. Hydroxyl A chemical group composed of an oxygen atom bound to a hydrogen atom (i.e., -OH). Hypersaline Water with a salinity in excess of that at which halite will spontaneously precipitate. Hypoxic Waters with dissolved oxygen concentraUons less than 2 to 3 ppm (2mL/L). 

Lagoonal Of lagoons, which are semi-isolated bodies of seawater trapped between coral reefs and volcanic islands or between the mainland and barrier islands. Seawater in lagoons tends to be hypersaline. 

In order to be successful in finding a biocatalyst that is adapted to the required process conditions, one could sample at a site where similar conditions apply. As such sampling sites with low biodiversity, but high selection pressure such as hypersaline ponds, acidic or alkaline lakes, deserts, hot springs or sites polluted with chemicals are particularly useful. 

Brominated fatty acids are rare in nature. They have been found in sponges and other marine animals. Recently, the presence of (5E, 7E)-18-bromo-octadeca-5,17-diene-15-ynoic acid (221) and 18-bromo-octadeca-5,7,17-triynoic acid (222) has been described in a halophilic (present in hypersaline environments) terrestrial organism, the Central Asian lichen Acorospora gobiensis [171]. 

Fulvic acid was isolated in Big Soda Lake above and below the chem-ocline, which occurs at 34-m depth. Water near the lake surface has moderate salinity and is oxygenated, whereas water below the chemocline is hypersaline and anoxic (17). In spite of these environmental differences the chemical character of the fulvic acid from above or below the chemocline did not vary, as determined by elemental analyses and NMR spectrometry. 

Not all measures of salinity convey the same degree of salinity. For example, compare Orca Basin, the Great Salt Lake, the Dead Sea, and Basque Lake (Table 5.1). All four of these waters contain about the same salinity % [25.1-26.4% salt (wt/wt)]. Note, however, that Basque Lake has a much more favorable (for life) aw (0.919) compared with Orca Basin (0.774), Great Salt Lake (0.776), and, especially, the Dead Sea (0.690). The impact of salts on life depends on the anions and cations and their charges and molecular weight. Bacterial sulfate reduction occurs with salt concentrations up to 24% (Oren 1988), but chloride salt solutions at such concentrations deals much more harshly with life. Only the most halophilic organisms can live in the Dead Sea (Table 4.2). The Dead Sea was called dead because it was only in 1936 that life forms (e.g., bacteria, algae, yeast) were first isolated from this hypersaline water (Ventosa et al. 1999). 

Salinity exerts a positive influence on the rate of the addition reaction depending on the polarizability of the organic molecule. This effect is pronounced for unsaturated molecules containing a terminal carboxyl group. These results suggest that hypersaline palaeoenvironmental conditions would have favored organosulfur formation by the Michael addition mechanism. 

The other major reactant in Equation 1 is sulfate (SO42 ). Sulfate concentrations are highly variable in lake waters, from 3 x 10 5 mol/L in soft-water lakes in crystalline-rock drainage basins to 1.6 mol/L in hypersaline lakes (2.). In productive, freshwater lakes, sulfate reduction typically goes nearly to completion (5.). As sulfate concentrations increase, amounts of organic matter eventually become insufficient for complete sulfate reduction to occur. This is the case in "normal" marine sediment where a linear relation between total reduced sulfur and organic-carbon concentrations is observed. Sea-water sulfate concentration is 0.028 mol/L and the ratio of total reduced sulfur to organic-carbon concentrations (often referred to as S/C) in marine sediment is 0.33 ( ). ... 

In these clastic sediments the dominant form of sulfur is pyritic, while organic sulfur is usually present only in trace amounts. For this reason, much work on sulfur in these sediments focuses on pyrite formation and its crystallization has been studied in detail by Berner (IT), Sweeney and Kaplan (12). Rickard (13). Rickard (14) and others. Under saline and hypersaline conditions precipitation of monosulfides may be the initial step. Sulfur is then added to these precipitates, converting them to pyrite. Laboratory studies indicate that if griegite is present in the original precipitate, sulfurization may produce framboidal aggregates (12). Conversion may depend on chemical factors such as H2S concentrations (9). In contrast, in conditions that are undersaturated with respect to monosulfides, but supersaturated with respect to pyrite, pyrite may form directly and rapidly from... 

A record was maintained of the size of each pyrite occurrence. Core 1 shows a gradual increase in the percentage of pyrite particles less than six microns in size whereas core 3 shows a decrease in the percentage of the same size pyrite particles (Table I). Core 2 shows no consistent pattern. The tidal creek with an abundance of sulfate in a reducing environment appears to produce more pyrite of smaller sizes. On the marsh panne, larger pyrite particles are formed in this hypersaline, high alkalinity environment. 

---