Oxygen - Solubility in Fresh and Sea Water vs. Temperature
Solubility of oxygen in equilibration with air in fresh water and seawater (salt water) - pressures ranging 1 - 4 bar abs.
Normally dissolved oxygen from air in fresh water and sea water (salt water) at pressures ranging 1 - 4 bar abs are indicated in the diagrams and tables below.
Note! - in air with normal composition the oxygen partial pressure is 20% of the total pressure. This results in 20% oxygen dissolution from air compared to pure oxygen.
The salinity of seawater in oceans ranges 30 to 50 parts per thousand (30,000 - 50,000 ppm), on average 35 ppt.
- 35 g dissolved salt / kg sea water = 35 ppt = 35 o/oo = 3.5% = 35,000 ppm
The salinity is not uniform and vary with location and depth. Water with salinity between freshwater and seawater is called brackish.
Oxygen Solubility in Fresh Water - Salinity ~ 0
| Salinity ~ 0 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pressure abs | mm Hg | 760 | 1520 | 3040 | ||||||
| psi | 14.7 | 29.3 | 58.7 | |||||||
| bar | 1 | 2 | 4 | |||||||
| kPa | 101.1 | 202.2 | 404.3 | |||||||
| Temperature | Solubility | |||||||||
| oC | oF | μMol | mg/l | ml/l | μMol | mg/l | ml/l | μMol | mg/l | ml/l |
| 0 | 32 | 457 | 14.6 | 10.2 | 913 | 29.2 | 20.5 | 1823 | 58.4 | 40.9 |
| 5 | 41 | 399 | 12.8 | 9.1 | 798 | 25.5 | 18.2 | 1595 | 51.1 | 36.4 |
| 10 | 50 | 353 | 11.3 | 8.2 | 705 | 22.6 | 16.4 | 1411 | 45.1 | 32.8 |
| 15 | 59 | 315 | 10.1 | 7.5 | 630 | 20.2 | 14.9 | 1260 | 40.3 | 29.8 |
| 20 | 68 | 284 | 9.1 | 6.8 | 568 | 18.2 | 13.7 | 1137 | 36.4 | 27.3 |
| 25 | 77 | 258 | 8.3 | 6.3 | 517 | 16.5 | 12.6 | 1034 | 33.1 | 25.3 |
| 30 | 86 | 236 | 7.6 | 5.9 | 473 | 15.2 | 11.8 | 947 | 30.3 | 23.6 |
| 35 | 95 | 218 | 7 | 5.5 | 436 | 14 | 11 | 872 | 27.9 | 22.1 |
| 40 | 104 | 202 | 6.5 | 5.2 | 404 | 12.9 | 10.4 | 808 | 25.9 | 20.8 |
| 45 | 113 | 189 | 6 | 4.9 | 375 | 12 | 9.8 | 751 | 24 | 16.9 |
| 50 | 122 | 177 | 5.6 | 4.6 | 355 | 11.3 | 9.3 | 710 | 22.7 | 18.7 |
Oxygen Solubility in Seawater - Salinity ~ 35
| Salinity ~35 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Pressure abs | mm Hg | 760 | 1520 | 3040 | ||||||
| psi | 14.7 | 29.3 | 58.7 | |||||||
| bar | 1 | 2 | 4 | |||||||
| kPa | 101.1 | 202.2 | 404.3 | |||||||
| Temperature | Solubility | |||||||||
| oC | oF | μMol | mg/l | ml/l | μMol | mg/l | ml/l | μMol | mg/l | ml/l |
| 0 | 32 | 349 | 11.2 | 7.8 | 699 | 22.4 | 15.7 | 1399 | 44.8 | 31.3 |
| 5 | 41 | 308 | 9.9 | 7 | 616 | 19.7 | 14.1 | 1233 | 39 | 28 |
| 10 | 50 | 275 | 8.8 | 6.4 | 550 | 17.6 | 12.8 | 1099 | 35.2 | 25.6 |
| 15 | 59 | 248 | 7.9 | 5.9 | 495 | 15.9 | 11.7 | 991 | 31.7 | 23.4 |
| 20 | 68 | 225 | 7.2 | 5.4 | 450 | 14.4 | 10.8 | 901 | 28.8 | 21.7 |
| 25 | 77 | 206 | 6.6 | 5 | 413 | 13.2 | 10.1 | 826 | 26.4 | 20.2 |
| 30 | 86 | 190 | 6.1 | 4.7 | 381 | 12.2 | 9.5 | 761 | 24.4 | 18.9 |
| 35 | 95 | 176 | 5.6 | 4.5 | 353 | 11.3 | 8.9 | 706 | 22.6 | 17.9 |
| 40 | 104 | 165 | 5.3 | 4.2 | 329 | 10.5 | 8.5 | 658 | 21.1 | 16.9 |
| 45 | 113 | 154 | 4.9 | 4 | 308 | 9.9 | 8 | 616 | 19.7 | 16.1 |
| 50 | 122 | 146 | 4.6 | 3.8 | 292 | 9.4 | 7.7 | 585 | 18.7 | 15.4 |
- dissolution of pure oxygen
