Dispersing agents, also called dispersants, are chemicals that
contain surfactants and/or solvent compounds that act to break
petroleum oil into small droplets. In an oil spill, these
droplets disperse into the water column where they are subjected
to natural processes, such as waves and currents, that help to
break them down further. This helps to clear oil from the
water's surface, making it less likely that the oil slick will
reach the shoreline. Heavy crude oils do not disperse as well as
light to medium weight oils. Dispersants should not be used on
gasoline or diesel spills for example. Dispersants are most
effective when applied immediately following a spill, before the
lightest materials in the oil have evaporated, however,
dispersant manufacturers have claimed that the "window-of-
opportunity" to apply dispersants effectively is widening.
Environmental factors, including water salinity and temperature,
and conditions at sea also influence the effectiveness of
dispersants. Studies have shown that most