Salinity refers to the saltiness of water caused by the dissolution of minerals in rocks, soils and decomposing plant material. The level of salinity in a river, for instance, depends on the geological and climatic environments through which the river flows. Salinity increases downstream, as salts are continuously added through natural and anthropogenic processes such as mining, industry and agriculture, but are only minimally removed through technological interventions or diluted by precipitation.
High levels of salinity can lead to the "salinisation of irrigated soils, diminished crop yields, increased scale formation and corrosion in domestic and industrial water pipes, and changes in the biotic communities." 1 000 mg/L is considered moderate salinity and is generally tolerated by humans; however, at levels above 3 000 mg/L (high salinity) fatal intestinal damage and renal damage can occur (DEAT 2009).
Salt encrusted soil in the Kalahari
( click to enlarge )