Composition of seawater
The average concentration of the 22 most common elements and ions of natural seawater at a specific density of 1.025 kg/l.
| Element / Ion | Amount | Unit |
| Chloride - Cl | 19.8 | g/l |
| Sodium - Na | 11.0 | g/l |
| Sulfate - SO4 | 2.8 | g/l |
| Magnesium - Mg | 1.3 | g/l |
| Calcium - Ca | 431 | mg/l |
| Potassium - K | 410 | mg/l |
| Hydrogencarbonate - HCO3 | 148 | mg/l |
| Bromide - Br | 72 | mg/l |
| Strontium - Sr | 8 | mg/l |
| Boron - B | 4.6 | mg/l |
| Silicon - Si | 3 | mg/l |
| Fluoride - F | 1.3 | mg/l |
| Nitrate - NO3 | 0.5 | mg/l |
| Lithium - Li | 174 | µg/l |
| Rubidium - Rb | 123 | µg/l |
| Phosphorus - P | 13 | µg/l |
| Barium - Ba | 12 | µg/l |
| Molybdenum - Mo | 10 | µg/l |
| Iodide - I | 5 | µg/l |
| Arsenic - As | 2 | µg/l |
| Vanadium - V | 1 | µg/l |
| Titanium - Ti | 1 | µg/l |