Marine pollution is the introduction by man, directly or indirectly, of substances into the sea that are harmful to the marine environment. Marine pollution results in harm to living resources such as fish and marine life, hazards to human health, hindrance to marine activities like fishing, shipping, and oil drilling, and reduction of amenities such as beaches, boating, and water sports.
For many years it was assumed that the oceans could take all the waste that was dumped into them. This was true up to a certain extent… until the turn of the last century when marine activity was limited. As the population increased, industrialization and economic activities also increased, including marine activities like fishing, shipping, oil drilling, development of ports and harbors, passenger travel, and exploitation of the sea bed for minerals. These activities consequently generated waste grew to such an extent that marine pollution become extremely evident.
The first legislation against marine pollution was enacted by United Kingdom in 1923 and was known as the “Oil in Navigable Water Act.” Oil had become a major source of energy replacing coal and it was not only transported in larger volumes, but it also found favor as the fuel for marine diesel engines as well. It has led to increased marine pollution just as the transportation of oil as a cargo led to waste oils being generated as residues in tanks after discharging of cargo (as well as from the main engine).
The residues in the tank were discharged into the sea either during cleaning operations or when ballasting the tanks and discharging the “dirty ballast” into the sea before loading again.
At one point of time it was estimated that about 500,000 barrels of oil were being discharged into the sea. A new method for reducing the pollution was adopted called “Load-on-Top." In this method every oil tanker will be provided with a slop tank having a capacity of between 0.8 and 3 percent of the oil carrying capacity of the ship.
After cleaning the cargo tanks, dirty ballast residues and tank washing are transferred to this slop tank where they are allowed to stand for an adequate period without turbulence. The oil and water separates out and after determination of the oil/water interface by a detector, the water is pumped out from the bottom in compliance with regulations. The remaining oil residues are transferred to the shore reception facility or, if the new cargo is compatible, it can be loaded on top of this residue.
See how many pieces of plastic you can find in this small sample of stuff that washed ashore after a storm. This is all over Ocean Beach in San Francisco. For more on plastic in the ocean and what it does to our food chain (and ultimately us humans), just Google or Bing "plastic ocean" or "Great Pacific Garbage Patch" or "North Pacific Gyre"
So in order to avoid pollution by oil, cargo, and garbage the IMO introduced MARPOL regulations on which the discharge criteria are mentioned. So there is a need for record retention of the discharged items on board.
Record Retention of the Discharged Items On Board
According to MARPOL regulations, every ship has to maintain records of the following:
- Oil record book
- Cargo record book
- Garbage record book
Oil Record Book
The oil record book is in two parts. One is for the discharge of engine room bilges and the other is for the discharge of oil cargo wash from the slop tanks.
Oil Record Book Part 1:
Applicable for all ships, the following machinery space operations shall be recorded in the Part 1 of the oil record book.
- If there is any ballast or cleaning of fuel tanks, it should be entered in the oil record book.
- Any discharge of dirty ballast or clean water from fuel tanks should be entered.
- Collection and disposal of sludges from engine room, bilge waters, and other oil residues should be included.
- Automatic or non-automatic disposal of bilge water passing through oil water separator should be noted in it.
- Accidental or exceptional discharge of oil substances in the sea should be entered.
- Bunkering operation and the amount of reserve oil on board should be entered during and after bunkering.
- If any failures of filtering equipment like the oil/water separator, its alarm, and stop devices should be made a note.
Oil Record Book Part 2:
Applicable for all oil tankers carrying cargo, oil and ballast operation of tankers shall be recorded in this part 2 of the oil record book.
- Entries of loading and unloading of cargo oil should be made.
- If there is any internal transfer cargo oil inside the tanks during the voyage, it should be entered.
- Crude oil Washing should be noted.
- Ballast operation of cargo tanks and the segregated ballast tanks is noted.
- If any cleaning of cargo tanks, it should be entered.
- Discharge of ballast water should be entered.
- Discharge of water from slop tanks and the disposal of residues and oily mixtures are entered.
- Failure of Oily Water Discharge Monitoring Control Systems.
- If any oily water or residues remain after the tank washing and the delivery to the reception facilities, this should be noted.
Cargo Record Book
It is applicable for all types of ships especially for chemical tankers carrying Noxious Liquid Substances in Bulk is as per the MARPOL regulation for controlling the pollution.
The following operations shall be recorded in the Cargo Record Book:
- Loading of cargo, internal transfer, and unloading of noxious liquid cargo is entered.
- Mandatory prewash and the transfer of slop to reception facility are noted.
- Cleaning and ventilation of the cargo tanks should be entered.
- Note any discharge of tank washing into the sea.
- Ballasting and de-ballasting operations done during loading and discharge of cargoes should be noted.
- Accidental or exceptional discharge of cargos in order to save the life of crew and ship should be entered.
Garbage Record Book
It is applicable to all type of ships where the discharge of garbage is entered in the Garbage Record Book.
Any discharge or incineration operation of any garbage should be recorded in the book.
The entries include:
- Date and Time of disposal.
- Position of ship during the disposal of garbage.
- Description of the disposed garbage.
- Amount of garbage disposed in sea, incinerated or given to the reception facilities in ports should be noted.
- Amount of accidental escape or lost garbage and the reasons should be mentioned in the Garbage record book.
All these entries should be signed by the officer in-charge and at the end of these pages should be signed by the master. These records will be checked by the port state control and endorsed by them and it should be readily available for inspection. The record should be retained on board for at least three years after the last entry is made. In modern ships, all this record retention is maintained in the computer database onboard the ship, gathering the information from the control systems and operating systems of the ship. So there is no room for human error or malpractice in the recorded data onboard the ship.
- International Maritime Organisation – MARPOL
- Author's experience and expertise
- Image Wikipedia – Oil water discharge monitor and record retention
- Marpol Training – Oil Record Book
- Marpol – Oil Record Book