Understanding of MARPOL Annexes

Annex-1 

Focuses on the prevention of pollution during all oil transfer procedures.

Oil transfers are carried out in the machinery spaces of all ships and in the cargo spaces of tankers.

In general, ships over 400 GRT are permitted to discharge machinery space bilges into the sea, provided the ship is moving on passage, that is, she is en route.

This discharge of water is through an oily water separator, which has a discharge monitoring and control system.

The oil in the bilge overboard discharge does not amount to more than 15 parts per million.

For discharge of oily water from oily spaces of oil tankers of 10000 GRT, Annex-1 stipulates that the tanker is more than 50 nautical miles from the nearest land.

A tanker is preceding en route; the instantaneous rate of discharge of oil content does not exceed 30 litres per nautical mile.

The ship is not within a special area that includes the Mediterranean sea, the Baltic sea, the Black Sea, Red sea, the north sea, the Gulf of Aden, the Persian Gulf, The Antarctica area, the Oman area of the Arabian sea and the southern South African area.

Annex-2 

Concentrates on the cargo tanks of specialised carriers.

Unlike oil, noxious chemical compounds are not typically generated in the daily operation of a vessel.

More often than not pollution from chemicals at sea comes from the ship cargo rather than from the technical subsystems of the vessel.

Chemicals from the cargo tanks of specialised carriers however, do make their way into the sea through catastrophic hull failures and accidents, through loading and unloading of cargo and ore and through cargo tank washing.

Annex-2 sets specific discharge requirements for tank wash water.

Unless these criteria are met, this water must be retained onboard and discharged into an appropriate waste reception facility.

Special areas where the discharge of noxious liquids is not permitted are the Antarctic area and no discharges are allowed in this area.

Annex-3

Concerns the identification, labelling and safe stowage of harmful substances onboard in a packaged form.

Harmful substances are those substances that are identified as Marine pollutants in the International maritime dangerous goods code, IMDG code.

It relates to cargo carried by ships and therefore does not concern ships stores. Compliance with Annex-3 requirements generally falls on the shipper.

This Annex also calls for the ship to keep a detailed manifest of dangerous and or harmful packages cargos onboard.

Annex-4

Regulates the discharge of sewage to the sea. Sewage includes human, animal and or medical wastes also called black water.

International and local requirements regulate the discharge of sewage into the sea.

Annex-5 

Seeks to regulate the waste streams in order to reduce their impact on marine and coastal ecosystems.

The waste includes dunnage, lining, and plastic packing, food and food packing wastage, metal, paper, glass, medical waste, packaging for cleaning and maintenance compounds, etc.

When thrown overboard, this garbage often makes its way to coastlines or interfaces with marine life.

Annexe-6 

Details measures to reduce the emission of sulphur oxide, called SOx emissions and nitrogen oxides called NOx emissions from ships.

It also stimulates action to be taken to reduce the use and emission of ozone-depleting substances and other harmful air emissions.

This Annex calls for the sulphur content of marine bunkers to be kept at 4.5% worldwide.

In addition, it defines SOx emissions control areas, SECA, currently the Baltic and the north sea, where the sulphur content should not exceed 1.5 %.