Marine Environmental Protection
The regulatory framework
You must understand the MARPOL Annexes and what each controls: Annex I oil, Annex II noxious liquid substances, Annex III harmful substances in packaged form, Annex IV sewage, Annex V garbage, Annex VI air pollution. Know the meaning of a special area, the requirements for an oil record book, and the prohibition on discharging oily water without treatment through approved equipment. Understand the garbage management plan and the placards required on board.
Traps
A common trap is assuming that all garbage can be discharged beyond a certain distance from land; plastics can never be discharged. Another is confusing the oil record book with the garbage record book. Watch for questions on the 15 ppm limit for oily water discharge and the requirement for the oil discharge monitoring equipment. Also be careful with the meaning of 'nearest land' and the special area restrictions, and with the sulphur limits under Annex VI.
Worked rule of thumb
For garbage, remember the simple hierarchy: plastics never overboard; other garbage only where the Annex permits and beyond the specified distance from land, and never in a special area unless the Annex allows. For oily water, the rule is that discharge must pass through the oily water separator and meet 15 ppm, with the operation recorded in the oil record book. If in doubt, retain on board and land ashore. Accurate records are evidence of compliance and are checked at every port state control inspection.