Old Carthusian;
A reading of the early stages of the investigation reveals that the Brazillian authorities investigated it and concluded that it was not kerosine and this was not linked to the accident.
The ocean surface is home to numerous oil slicks, mostly from ship's leaking propeller tube and rudder glands. The "pollution spot" to which you are presumably referring, is not one that was originally investigated by the Brazilian Navy. Those investigated slicks were located well to the SSE of the one observed by satellite.
mm43