Boron occurs in nature exclusively in the form of boron compounds. With an average molar concentration of 4,16.10^-4 mol/l, boron is the eighth most common element in marine water. Expressed in mass units its average concentration is 4,5.10^-3 g/l (4,5 mg/l).

Iodine occurs on Earth exclusively in the form of iodine compounds, primarily diluted in salt-water and freshwater. With an average molar concentration of 4.10^-7 mol/l, iodine is the eighteenth most abundant element in sea water. Expressed in mass units, the iodine concentration ranges between 2,5.10^-5 - 6,4.10^-5 g/l (0,025 - 0,064 mg/l).

Potassium occurs in large amounts in the earth crust, while in seawater and in living organisms exclusively in the form of potassium compounds. With an average molar concentration of 1,02.10^-2 mol/l (expressed in mass units: 399 mg/l) potassium is the eighth most abundant element in seawater.

Nitrogen primary form on Earth is molecular nitrogen. With an average molar concentration of 2,25.10^-5 mol/l is nitrogen the fifteenth most common element in sea water. Expressed in mass units, the nitrogen concentration ranges between 0 and 45.10^-6 g/l (0 - 45 μg/l).

Due to its high reactivity, phosphorus occurs in nature only in the form of phosphorus compounds, to the greater extent in the minerals of Earth crust. According to its average molar concentration of 1,6.10^-6 mol/l, phosphorus is the sixteenth most abundant element in seawater. Expressed in mass units its average concentration is 4,96.10^-5 g/l (50 μg/l).