The most abundant gas dissolved in the ocean is nitrogen.
The ocean acts as a vast reservoir for atmospheric gases, absorbing them from the air at its surface. The amount of each gas that dissolves into seawater is primarily influenced by its concentration (or partial pressure) in the atmosphere and its solubility in water.
Atmospheric Composition and Gas Dissolution
Gases from the atmosphere dissolve into the ocean's surface layer. The partial pressure of a gas in the atmosphere dictates its tendency to enter the water until a state of equilibrium is reached. Here's a breakdown of the major atmospheric gases and their relative proportions:
| Gas | Atmospheric Percentage (by volume) | Partial Pressure (Torr) at Sea Level |
|---|---|---|
| Nitrogen | 78.03% | 593.02 |
| Oxygen | 20.99% | 159.52 |
| Argon | 0.94% | 7.144 |
| Carbon | 0.03% | 0.228 |
Why Nitrogen Dominates in the Ocean
Despite nitrogen having a lower solubility in water compared to some other gases like oxygen, its overwhelming abundance and high partial pressure in the atmosphere mean that it dissolves into seawater in the largest quantities by volume. It accounts for the largest proportion of dissolved gases in the ocean.
While other gases like oxygen are vital for marine life and carbon gases play a critical role in ocean chemistry and global climate regulation, their overall dissolved volume in the ocean is less than that of nitrogen.
