Salinity
The concentration of dissolved salts in water, typically measured in parts per thousand (ppt) or practical salinity units (PSU).
Salinity is a crucial factor in marine environments, as it influences the density, buoyancy, and overall chemistry of seawater. It is primarily determined by the amount of dissolved salts, such as sodium chloride, magnesium, calcium, and potassium, present in the water. In the open ocean, salinity typically ranges from 34 to 37 parts per thousand (ppt), but it can vary significantly in coastal areas, estuaries, and enclosed seas due to factors such as freshwater inflow from rivers, evaporation rates, and precipitation.
Higher salinity levels are often found in regions with high evaporation and low freshwater input, such as the Red Sea, while lower salinity levels occur in areas with significant freshwater influx, such as the Baltic Sea. Salinity plays a key role in ocean circulation, as it affects the density of seawater, which in turn drives thermohaline circulation—a global system of ocean currents that helps regulate climate. Additionally, salinity impacts marine life, as different species are adapted to specific salinity ranges. For instance, some organisms thrive in high-salinity environments, while others, such as those in estuaries, are adapted to brackish waters where salinity is lower. Understanding and monitoring salinity is vital for marine navigation, fisheries, and environmental conservation efforts.
