Chloride, magnesium, sodium, sulfate, calcium, bicarbonate and potassium are the most abundant ions in sea water. These ions form the bulk of seawater, while oxygen and water form the remaining portion. The ionic makeup of seawater influences its salinity, saltiness, temperature and buoyancy.
In addition to determining the saltiness and composition of seawater, the most abundant ions have a great deal to do with the creation of different habitats that support various life forms. Some species of plants and animals are better suited to salty sea water, while others thrive in less salty and more oxygenated waters.
Sea water ions share common colligative properties that impact the surrounding environment and the biodiversity found there. These properties include the ability to lower heat in surrounding waters and slow evaporation rates, lower the freezing point of water and increase osmotic pressures by increasing salinity levels. The effects of these colligative properties vary depending on the location of water, time of year and the presence or absence of other chemicals. Oceans generally maintain an equilibrium of physical and chemical composition that is achieved by the continual addition and removal of ions from local environments. This process occurs over a long period of time, sometimes taking up to 200 years to complete.