Salinization and Saline Environments

One of the most conspicuous phenomena of water-quality degradation, particularly in arid and semi-arid zones, is salinization of water and soil resources. The salinization is a long-term phenomenon, and during the last century many aquifers and river basins have become unsuitable for human consumption owing to high levels of salinity. Future exploitation of thousands of wells in the Middle East and in many other water-scarce regions in the world depends to a large extent on the degree and rate of salinization. Moreover, every year a large fraction of agricultural land is salinized and becomes unusable. Salinization is a global environmental phenomenon that affects many different aspects of our life (Williams, 2001a, b): changing the chemical composition of natural water resources (lakes, rivers, and groundwater), degrading the quality of water supply to the domestic and agriculture sectors, contribution to loss of biodiversity, taxonomic replacement by halotolerant species (Williams, 2001a, b), loss of fertile soil, collapse of agricultural and fishery industries, changing of local climatic conditions, and creating severe health problems (e.g., the Aral Basin). The damage due to salinity in the Colorado River Basin alone, for example, ranges between $500 and $750 million per year and could exceed $1 billion per year if the salinity in the Imperial Dam increases from 700 to 900 mg l^-1 (Bureau of Reclamation, USA). In Australia, accelerating soil salinization has become a massive environmental and economic disaster. As such, Western Australia is ‘‘losing an area equal to one football oval an hour’’ due to spreading.