WATER SALINITY

Based on their content in Total Dissolved Solids (expressed in parts-per-million, (ppm)), the US Geological Survey classification distinguishes waters as: Fresh (<1000 ppm); Slightly saline (1.000 - 3.000 ppm); Moderately saline (3.000 - 10.000 ppm); Very saline (10.000 - 35.000 ppm); Brine (>35.000 ppm. Water saturated or nearly so with salt). The use of the term "salinity" (and its determination) can vary among hydrologists, geologists, limnologists, oceanographers, marine biologists and experts in aquatic chemistry. There are significant variations in composition of constituents and their concentrations in natural waters. Bicarbonates and calcium predominate in freshwaters, while chlorides, sodium, and sulphate prevail in marine waters. As a general rule, inland waters (less than 1 ppt) can be distinguished from brackish (from 1 to 34 ppt) and marine waters (35 ppt). The distinction between inland and coastal waters is important given the many wetlands, lagoons, estuaries, etc. in the coastal zone. There are saline inland waters which may have values for "salinity" higher than marine waters. Choudhury and Jansen (1997)