An oil spill will move in the same direction and at a similar speed as the water. It is moved by currents, tide and wind. Biodegradation Many species of marine micro-organisms or bacteria, fungi and yeasts feed on the compounds that make up oil. The rate of biodegradation depends on the temperature of the oil and water mixture. Evaporation Causes some of the oil to transfer to the atmosphere.
Lighter hydrocarbons evaporate more rapidly than heavy components.
Weathering Is a progressive series of changes in oil characteristics caused by physical, chemical and biological processes. The rate of weathering is highly dependent on the type of oil spilled - the lighter it is, the faster it is likely to weather. The spilled oil is spread into the upper layers of the water column by natural wave action. The chemical combination of hydrocarbons with oxygen is known as oxidation. Oxidation is slow compared with other weathering processes.