Salinity, of groundwater

Figure 10 The dryland salinization cycle (the Australian model) (1) salt accumulation and precipitation of minerals (2) selective dissolution and transport of soluble salts in the vadoze zone (3) storage of salts influenced by soil permeability (4) leaching and salinization of groundwater (5) rise of saline groundwater (6) capillarity evaporation of rising groundwater (7) soil salinization and (8) lateral solute transport and salinization of streams and rivers (after Fitzpatrick et ah, 2000).

Hsissou Y., Mudry J., Mania J., Bouchaou L., and Chauve P. (1999) Use of the Br/Cl ratio to determine the origin of the salinity of groundwater an example from the Souss Plain, Morocco. Sujf. Geosci. 328, 381-386. 

Adyalkar, P. G., Ghosh, P. C., and Mehta, B. C., 1981, On the salinity of groundwater in South 24 Parganas District, West Bengal, India in van Duijvenbooden, W., Glasbergen,... 

Polemo, M., S. Buio, and S. Paoleiti. 1980. Evaluation of ionic strength and salinity of groundwaters Effect of the ionic composition. Geochim. Cosmochim. Acta 44(6) 809-14. 

A distinguishing feature of a sabkha is the presence of salt. Normally the salinity of groundwater rapidly inereases in a landward direction, with the result that the creation of salt crystals, caused by evaporation and desiccation, can form relatively hard crusty surfaces. The salt encrusted surfaces are sufficiently strong and durable. They become impassable upon wetting from rainfall or storm tides. In general a soil with a salt content equal to or more than 0.3% can be defined as a saline soil (Naifeng 1994). Salt can also be transported by wind. 

Ra in the water sample and fm is the fraction of the endmember remaining in the sample. Age determinations calculated in such a manner reflect the time elapsed since the water sample became enriched in Ra by the discharge of groundwater. " Ra is regenerated on the order of days. The fraction /em can be estimated either from salinity signal or from the distribution of isotopes, but this term can be difficult to... 

Other factors affecting performance include the presence of toxic material, the redox potential, salinity of the groundwater, light intensity, hydraulic conductivity of the soil, and osmotic potential. The rate of biological treatment is higher for more permeable soils or aquifers. Bioremediation is not applicable to soils with very low permeability, because it would take a long time for the cleanup process unless many more wells were installed, thus raising the cost. 

Garrels and Mackenzie wanted to test whether simple evaporation of groundwater discharging from the mountains, which is the product of the reaction of rainwater and CO2 with igneous rocks, could produce the water compositions found in the saline alkaline lakes of the adjacent California desert. They began with the mean of... 

Analysis for such isotopes as carbon and deuterium has been conventionally used to assess the relative age of groundwater, and in evaluating its origin (i.e., meteoric, juvenile, formation, etc.), chemistry, and total salinity. Isotope composition of ground-water and surface water has also been used to correlate between areas of precipitation and groundwater, thus providing an indication of source area(s) of recharge. 

The contamination of groundwater can negate any existing use that water may have, or prevent its future use. Furthermore, if not prevented and controlled, salinisation can affect nearby crops, pastures, infrastructure and buildings. The impacts of salinity have been widely studied and will not be discussed here. 

The salt content of groundwater, surface water, and soils is a major factor in determining their benefit to the community, the economy, and the environment. In many areas around the globe, increasing demand for water has created tremendous pressures on water resources, which resulted in lowering water levels and increasing salinization. 

Salama RB, Otto CJ, Fitzpatrick RW (1999) Contributions of groundwater conditions to soil and water salinization. Hydrogeol J 7 46-64... 

A major outcome of the abovementioned studies is the importance of pH and notably of the salinity of the groundwater controlling colloid concentrations and, consequently, the relevance of colloids for radionuclide transport. The pH-dependent colloid stability varies considerably for different colloid types. Experimental data for the relationship of the stability ratio W... 

Sorption on magnetite as a function of groundwater composition shows that, under anoxic conditions, technetium removal from solution is essentially complete after 50 days, with the exception of solutions containing phosphate ions. As pointed out earlier, phosphate was used instead of carbonate, as both are known to form anionic complexes with Tc(IV) (9). In these studies, the presence of humic acid did not affect its sorption. Strong saline solutions (up to 34 000 mg/L Cl) do not have a marked effect on the rate of technetium removal from solution either, as evident from Figure 8. 

Figure 7.27. Maps showing the thickness of (A) the interface-bounded lens in feet below the water table to the iso-surface of 50% relative salinity, and (B) the freshwater nucleus in feet below the water table to the iso-surface of 1 % relative salinity for groundwaters in the central region of Bermuda. (After Vacher, 1974.)...

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