The percentage of dissolved salts, or salt minerals, present in a sample of water is called salinity.
Salinity varies depending on how much salt has dissolved in the water—until the water reaches its saturation point, when it can contain no more salt.
Factors that help determine the salinity of water include evaporation, precipitation, and land and ice run-off.
Evaporation and land run-off increase water’s salinity. Precipitation and melting ice reduce it.