Saline environment

Transition Temperature. The order-disorder transition temperature mid-point T is also determined both by the environment - salinity, pH value, and the nature of the ions in solution, and the structure of the polymer - charge, pyruvate, succinate and acetate content. Most published work describes the low salinity behaviour of such polymers, and has shown that for xanthan, the transition temperature exceeds 100 C as the salinity exceeds about 1 per cent sodium chloride (10). 

Metal Environment Salinity (%o) Concentration (nmol liter ) Reference"... 

Open-ocean waters have a narrow range of salinities (32-37) and most are near 35. In estuaries, values fall to less than 1 approaching the freshwater end-member. In hypersaline environments salinities can exceed those of seawater, reaching values greater than 300. 

Yokoya et al. (1999) investigated growth and tolerance of G. vermiculophylla, taken from the marine environment (salinity varied between 29 and 34 psu), under a variation of temperature (5-30°C), salinity (5-60 psu), and photon irradiance (20-100 /imol photons m /s ). 

Numerous theories exist as to how the Chilean deposits formed and survived. It has been postulated that the unique nitrate-rich caUche deposits of northern Chile owe their existence to an environment favorable to accumulation and preservation of the deposits, rather than to any unusual source of the saline materials (2). The essential conditions are an extremely arid climate similar to that of the Atacama desert in the 1990s, slow accumulation during the late Tertiary and Quaternary periods, and a paucity of nitrate-utilizing plants and soil microorganisms. 

This removal may also include diffusion of soluble U(VI) from seawater into the sediment via pore water. Uranium-organic matter complexes are also prevalent in the marine environment. Organically bound uranium was found to make up to 20% of the dissolved U concentration in the open ocean." ° Uranium may also be enriched in estuarine colloids and in suspended organic matter within the surface ocean. " Scott" and Maeda and Windom" have suggested the possibility that humic acids can efficiently scavenge uranium in low salinity regions of some estuaries. Finally, sedimentary organic matter can also efficiently complex or adsorb uranium and other radionuclides. 

For dust- and chemical-laden atmospheres as in cement plants, chemical industries and refineries and areas in alkaline and saline environments reduce the repreasing intervals by roughly 30%. 

As will have become apparent, nickel and corrosion-resistant nickel alloys have wide ranges of application, particularly in industries where strongly acidic, strongly alkaline or strongly saline environments are encountered. Table 4.29 lists some of the more important applications in those industries where these conditions most frequently arise, i.e. in the chemical, petrochemical, oil and gas, nuclear and conventional power generating, textile, paper, marine, desalination and food processing industries. The list is by no means exhaustive and there are many other applications of a similar nature in these and other industries. The table should, nevertheless, serve... 

Most of the published evidence suggests that marine fouling cover— particularly where it is continuous and well established — reduces corrosion rates of steels . Indeed, 35%o seawater is by no means the most corrosive of saline environments towards steel. Brackish water, as found in estuarine or certain other coastal areas, is considerably more aggressive towards steel, and careful design measures should be taken to ensure that effective corrosion control is achieved in such circumstances. 

The problem of the high resistance polarisation decreases with increasing water content and salinity, such as prevails during immersion in seawater, where these anodes are particularly useful. Since no problems of burial arise in that environment an endless variety of disused iron-ware has been utilised for anodes, e.g. pipes, piling, machinery, rails and even obsolete shipping which has not been economic to salvage. Consumption rates in excess of the theoretical value have been reported for steel in different waters . 

Late Pleistocene Lake Saline Compared with Those in Lake Michigan S Sediments. Environ. Geo. 1973 14 pp. 

In arid environments, where the soluble products of weathering are not completely removed from the soil, saline solutions may circulate in the soil as well as in rock fractures. If upon evaporation the salt concentration increases above its saturation point, salt crystals form and grow (Goudie et al, 1970). The growth of salt crystals in crevices can force open fractures. Salt weathering occurs in cold or hot deserts or areas where salts accumulate. Boulders, blocks. 

Heaton, T.H.E. 1987 The N/ N ratio of plants in South Africa and Namibia relationship to climate and coastal/saline environments. Oecologia 74 236-246. 

Cells exposed to saline stress encounter reduced water availability, ion toxicity and reduced availability of essential nutrients. These cellular level responses are also reflected at the whole-plant level. An understanding of these cellular responses will undoubtedly contribute to an understanding of the response of a plant growing in a saline environment. 

Cells exposed to excessive levels of salinity have to acquire essential nutrients from a milieu with a preponderance of ions that are potentially toxic and non-essential. In this ionic environment the success of a plant cell will require intracellular tolerance and/or specific acquisition of nutrients essential for normal metabolic functioning. The cell is also exposed to an unfavourable water balance with an absolute requirement to maintain an internal osmotic regulation that favours uptake of water into the cell (Stavarek Rains, 1984 ). 

Osmotic adjustment by plant cells in response to an increasing saline environment can be mediated by an alteration in intracellular concentrations of both inorganic and organic ions (Wyn Jones, 1980,1984 Aspinall, 1986 Flowers Yeo, 1986 Grumet Hanson, 1986 Moftah Michel, 1987). 

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