The Effects of Chemical Dispersion on Long-Term Weathering of Crude Oil in Cold Seawater

The effects of chemical dispersion on crude oil weathering in cold seawater have been studied in a mesoscale simulator (1,675 L) under ambient air conditions. Oil droplets dispersed in the contained water column were rapidly biodegraded during the fall experiment whereas the bacterial activity was reduced by at least one order of magnetude in experiments conducted below an ice cover. Undispersed oil formed a water in oil emulsion (chocolate mousse) very resistant to weathering processes. During winters mousses were trapped in ice and recovered almost unchanged 3 to 4 months later.