Exploring Our Fluid Earth

Small quantities of low-solubility substances, such as oil, can remain in a solvent such as water, either as droplets or as single suspended molecules. 

 

Molecules of nonpolar substances such as the vital gases of air, oxygen (O₂) and nitrogen (N₂), dissolve in sufficient quantity in water to sustain all living things in our rivers, lakes, and oceans. At 25°C a liter of seawater holds 5 mL of oxygen (0.007 g/L) and 10 mL of nitrogen (0.012 g/L).

 

SF 3-3 O2 gas bubbling out of solution

Photo courtesy of Annkatrin Rose

For example, wind and waves at sea will eventually break up an oil slick into particles (small droplets) and distribute them far and wide. This means that, although the oil may no longer be easy to see, it is being spread throughout the environment, imposing challenges for a variety of organisms.