MARPOL 73/78 Annex II, Regulations for the Control of Pollution by Noxious Liquid Substances in Bulk
Annex II came into force on 06.04.1987 and contains discharge conditions for four categories of noxious substances and requirements applicable to the construction and equipment of ships carrying such substances. Unlike oil, most chemicals or noxious liquids will mix with water and are not easily separated from it. The main principle of Annex II is to dilute cargo residues in seawater to prescribed limits depending on their pollution hazard and facilitate the distribution of discharges by utilising the wake of the ship. The discharges are required to be made below the water line and in such a way that the water/residue mixture is retained in the ship boundary layer and carried aft when en route to be distributed by the wake astern.