Mass transport
T he we a the r ing of t he oil, accidently spilled or continuously discharged into the s e a, is illustrated in Figure 2. Several of the processes
shown in Figure 2 have b e en eliminated from the model:
• Dissolution and chemical reaction. Nume rous investigators have
found that oil losses due to dissolution will be two or more orders
of magni tude smaller t h an from e v a p o r a t i o n .
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Photo-oxidation
is t he dominant chemical r e a c t ion, producing a r a ther complex
mixture of very soluble alcohols, k e t o n e s, aldehydes, and acids.
Even s o, oxidation will have only minor influence within the first
weeks of the spill.
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• Biodegradaton, consumption by plankton, sedimentation as fecal
pellets and on particles. T he weathering model intends only to
describe the fate of the oil at the sea surface.
• Sedimentation. In rough seas and in coastal waters oil may be
adsorbed on pa r t i cul a te ma t t er such as sand. If the density of the
oil exceeds t he density of t he seawater, t he oil will settle to the
b o t t om. T he low conc ent r a t ion of particulate ma t t er in the Nor th
Sea r ende rs s ediment a t ion negligible.
T he we a the r ing processes t aken into account in the model are
spr e ading, vertical and horizontal dispersion, evapor a t ion, emulsification (water u p t a k e ), and upwelling of dispersed oil to the surface.